How can I start Firefox with add-ons installed?

Create a Firefox profile and add required add-ons. 

Take ‘Firebug’ as an example, save the Firebug XPI into the C:FF_addons folder as firebug.xpi (Download XPI file from Firebug download page, right-click on the “Download Now” and save as C:FF_addonsfirebug.xpi).

Then create a Firefox profile and add Firebug add-on while instantiating FirefoxDriver as below:

   String firebugFilePath = "C:\FF_addons\firebug.xpi";
   FirefoxProfile profile = new FirefoxProfile();       
   profile.addExtension(new File(firebugFilePath));
   // Add more FF addons if required 
   WebDriver driver = new FirefoxDriver(profile);

How can I instantiate FirefoxDriver?

The FirefoxDriver can be instantiated as below:

WebDriver driver = new FirefoxDriver(); // Instantiate the class - org.openqa.selenium.firefox.FirefoxDriver

Sample code(Java Binding):

package tests;

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.firefox.FirefoxDriver;

public class FirefoxDriverSample {
	public static void main(String[] args) {
		// Instantiate the FirefoxDriver
		WebDriver driver = new FirefoxDriver();

		// Visit the Selenium-WebDriver FAQ site
		driver.get("http://seleniumwebdriverfaq.tumblr.com/");

		// Print the title of the page - It should print "Selenium-WebDriver FAQ's"
		System.out.println("Title of the page is: " + driver.getTitle());

		//Close the browser window
		driver.close();

		//Quit the driver
		driver.quit();
     }
}

What are the different implementations of WebDriver available?

Below are the WebDriver implementations available as off now:

1. HtmlUnitDriver
2. FirefoxDriver
3. InternetExplorerDriver
4. ChromeDriver
5. OperaDriver

6. AdroidDriver
7. IPhoneDriver

You can find out more information about each of these by following the links.

From where can I download set of Selenium tools?

Link below is where you can find the latest releases of all the Selenium components:

http://seleniumhq.org/download/