This error message...

An internal error occurred during: "Launching NewTest"
org.testng.eclipse.maven.MavenTestNGLaunchConfigurationProvider.getClasspath(Lorg/eclipse/debug/core/ILaunchConfiguration;)Ljava/util/List;

...implies that there was incompatibility between TestNG and Maven related classfiles.

Historically, this error would occur if while installing testng you have kept the checkbox for M2E Maven as checked.

The easiest approach to address this issue would be to reinstall the TestNG ensuring that the checkbox for M2E Maven is kept unchecked.

Yes, that's possible. You can create an annotation to specify the parameters this DataProvider should load from your XML.

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface XmlParameters {
   String[] value();    
}

@Test(dataProvider = "XMLFileLoader")
@XmlParameters({"username", "password"})
public void testSomething(String username, String password) {
    // implementation omitted for brevity
}

@DataProvider(name = "XMLFileLoader")
public static Object[][] getDataFromXmlFile(final Method testMethod) {
    XmlParameters parameters = testMethod.getAnnotation(XmlParameters.class);
    String[] fields = parameters.value();
    //load just the fields you want
    return new Object[][] { { "user1", "pass1" } };
}

This code is not "production ready", you should check if the annotation is not null before reading the values, and is probably better move the interface and the logic to load your xml to another class, so you can reuse on another tests.

Implement the IInvokedMethodListener interface and throw a SkipException when the threshold is reached. In the below code have used 30%.

public class MyMethodInvoke implements IInvokedMethodListener {

    private int failure = 0;

    @Override
    public void beforeInvocation(IInvokedMethod method, ITestResult testResult) {
        int testCount = testResult.getTestContext().getAllTestMethods().length; 
        if((failure * 1.0) / testCount > 0.3)
            throw new SkipException("Crossed the failure rate");
    }

    @Override
    public void afterInvocation(IInvokedMethod method, ITestResult testResult) {        
        if(testResult.getStatus()==ITestResult.FAILURE)
            failure++;
    }

}

@Listeners({package.MyMethodInvoke.class})
public class Test {

It works for tests in a single class, no idea how it behaves with tests in multiple classes in a suite. Or even for a parallel execution.

To quote TestNG's documentation:

Any @AfterMethod method can declare a parameter of type ITestResult, which will reflect the result of the test method that was just run.

You can use this parameter to check if the test succeeded or not:

@AfterMethod(groups = { "Regression" })
public void afterMethod(ITestResult result) {
   if (result.getStatus() == ITestResult.SUCCESS) {
        // Setting driver used to false as this test case is pass
        driverUsed.put("supportDriver", false);
        System.out.println("Test case is pass");
   }
}

It is impossible to depend on a method from different classes.

However, it is definitely possible to depend on a group from different classes. If you want to use XML, this is the documentation for that: http://testng.org/doc/documentation-main.html#dependencies-in-xml

First you have to create properties file with your different URLs

Then Add config File reader

public String applicationUrl_QA() {
        String applicationUrl = properties.getProperty("applicationUrl_QA");
        if(applicationUrl != null) return applicationUrl;
        else throw new RuntimeException("url not specified in the Configuration.properties file.");
    }

Then you can config all the environments like below

if(Env.equalsIgnoreCase("QA")){
            if(URL.equalsIgnoreCase("_QA")){
                driver.get(configFileReader.applicationUrl_QA());
}

then you have create seperate XMLs like below

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd">
<suite name="Suite" parallel="false" thread-count="5" verbose="1">

    <!--Values Chrome Firefox HLChrome HLFirefox HTMLUnit phantomJS-->
    <parameter name="browser" value="Firefox"/>

    <!--Values AdminURL StatementURL PatientURL-->
    <parameter name="URL" value="Value"/>

    <!--Values QA Dev Uat Prod -->
    <parameter name="Env" value="QA"/>
    <test name="AdminTests">
        <classes>
            <class name="tests.Test1"/>
        </classes>
         <classes>
            <class name="tests.test2"/>
        </classes>
    </test>
</suite>

Finally you have to call all the xmls using one xml file

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd">
<suite name="Suite" parallel="false" thread-count="5" verbose="2">
<suite-files>
    <suite-file path="File1_QA.xml"/>
</suite-files>
    <suite-files>
        <suite-file path="File2_UAT.xml"/>
    </suite-files>
</suite>

Another option is to use a suite-of-suites. I'll preface this by saying it's been a while since I've worked with this setup, but hopefully you'll find enough detail here to at least get started.

First, you'd define two (or more) suite XML files:

<suite name="Suite1">
    <test name="test1">
        <classes>
            <class name="fully.qualified.ClassName" />
        </classes>
        <methods>
            <include name="method1" />
        </methods>
    </test>
</suite>

and...

<suite name="Suite2">
    <test name="test2">
        <classes>
            <class name="fully.qualified.ClassName" />
        </classes>
        <methods>
            <include name="method2" />
        </methods>
    </test>
</suite>

Then, you'd define a suite-of-suites XML file:

<suite name="suite of suites">
    <suite-files>
        <suite-file path="Suite1.xml" />
        <suite-file path="Suite2.xml" />
    </suite-files>
</suite>

Do note, that the suite-file path value is the relative path from the current suite-of-suites XML file to the XML file you're calling. If they're in the same directory, simply the file name will suffice.

Additionally, both XML types do support the <parameter> tag. The standard suite XML will read both at <suite> and in the <test> levels, and I've found that <parameter> tags at the <suite> level on the suite-of-suites XML file will work as well.

Finally, on execution, you'd need only pass in the suite-of-suites XML file as your suite file argument.

EDIT: Here's how I was able to make my two suites run in parallel. The trick was setting up my main() method properly.

public class TestRunner
{
    public static void main(String[] args)
    {
        TestNG testng = new TestNG();
        TestListenerAdapter adapter = new TestListenerAdapter();
        List<String> suites = new ArrayList<String>();

        testng.addListener(adapter);
        suites.add(args[0]);
        testng.setTestSuites(suites);
        testng.setParallel("parallel");
        testng.setSuiteThreadPoolSize(5);
        testng.setOutputDirectory("path to output");
        testng.run();
    }
}

Then, on the command line:

java -jar ParallelSuiteDemo.jar SuiteOfSuites.xml

Note, my jar and all xml files were in the same directory with this configuration. The command line args and <suite-file> entries would need to be configured properly if you wish you use a directory structure.

This yielded my two suite.xml files running in parallel on a Selenium Grid.

There may be better ways of doing this, to be honest. This is just what worked for me when I was trying to do something similar.

I had the same problem, and found that it helps to set the field storing test case name in the method annotated with @BeforeMethod, using native injection of TestNG to provide method name and test parameters. The test name is taken from test parameters supplied by the DataProvider. If your test method does not have parameters, just report the method name.

//oversimplified for demontration purposes
public class TestParameters {
    private String testName = null;
    private String testDescription = null;

    public TestParameters(String name,
                          String description) {
        this.testName = name;
        this.testDescription = description;
    }

    public String getTestName() {
        return testName;
    }
    public String getTestDescription() {
        return testDescription;
    }
}

public class SampleTest implements ITest {
    // Has to be set to prevent NullPointerException from reporters
    protected String mTestCaseName = "";

    @DataProvider(name="BasicDataProvider")
    public Object[][] getTestData() {
        Object[][] data = new Object[][] {
                { new TestParameters("TestCase1", "Sample test 1")},
                { new TestParameters("TestCase2", "Sample test 2")},
                { new TestParameters("TestCase3", "Sample test 3")},
                { new TestParameters("TestCase4", "Sample test 4")},
                { new TestParameters("TestCase5", "Sample test 5") }
        };
        return data;
    }

    @BeforeMethod(alwaysRun = true)
    public void testData(Method method, Object[] testData) {
        String testCase = "";
        if (testData != null && testData.length > 0) {
            TestParameters testParams = null;
            //Check if test method has actually received required parameters
            for (Object testParameter : testData) {
                if (testParameter instanceof TestParameters) {
                    testParams = (TestParameters)testParameter;
                    break;
                }
            }
            if (testParams != null) {
                testCase = testParams.getTestName();
            }
        }
        this.mTestCaseName = String.format("%s(%s)", method.getName(), testCase);
    }

    @Override
    public String getTestName() {
        return this.mTestCaseName;
    }

    @Test(dataProvider="BasicDataProvider")
    public void testSample1(TestParameters testParams){
        //test code here
    }

    @Test(dataProvider="BasicDataProvider")
    public void testSample2(TestParameters testParams){
        //test code here
    }

    @Test
    public void testSample3(){
        //test code here
    }
}

EDIT: Based on the comments below, I realized a sample from report will be useful.

Extract from the report from running code above:

<testng-results skipped="0" failed="0" total="5" passed="5">
  <suite name="SampleTests" duration-ms="2818" started-at="<some-time>" finished-at="<some-time>">
    <test name="Test1" duration-ms="2818" started-at="<some-time>" finished-at="<some-time>">
        <test-method 
            status="PASS" 
            signature="testSample1(org.example.test.TestParameters)[pri:0, instance:org.example.test.TimeTest@c9d92c]"
            test-instance-name="testSample1(TestCase5)"
            name="testSample1" 
            duration-ms="1014"
            started-at="<some-time-before>" 
            data-provider="BasicDataProvider" 
            finished-at="<some-time-later>" >
            <!-- excluded for demonstration purposes -->
        </test-method>
        <!-- the rest of test results excluded for brevity -->
    </test>
  </suite>
</testng-result>

Note, that the value returned from getTestName() method is in the test-instance-name attribute, and not in the name attribute.

There's a difinition for @BeforeClass :

@BeforeClass
Run before all the tests in a class

And @FindBy is "executed" each time that you'll call the class.

Actually your @FindBy is called before the @BeforeClass so it won't work.

What i can suggest to you is to keep the @FindBy but let's start to use the PageObject pattern.

You keep your test's page and you create another class for your objects like :

public class PageObject{
  @FindBy(id = "j_idt5:nome")
  private WebElement inputNome;

  @FindBy(id = "j_idt5:idade")
  private WebElement inputIdade;

  // getters
  public WebElement getInputNome(){
    return inputNome;
  }

  public WebElement getInputIdade(){
    return inputIdade;
  }

  // add some tools for your objects like wait etc
} 

Your SeleniumTest'll looks like that :

@Page
PageObject testpage;

@Test(priority = 0)
public void digitarTexto() {

  WebElement inputNome = testpage.getInputNome();
  WebElement inputIdade = testpage.getInputIdade();

  inputNome.sendKeys("Diego");
  inputIdade.sendKeys("29");
}
// etc

If you're going to use this tell me what's up.