Are you sure your questions aren't answered by the documentation. This is is one of the more complete documentation files and pretty clearly explains when and why these methods exist and are called.http://developer.android.com/reference/ ... ivity.html
You will want to take note of the AndroidManifest.xml as well since there are many settings there. One in particular is important to understand and that is:
When you have the above line in your AndroidManifest.xml file for an Activity then the Activity won't restart when configuration changes occur. Config changes occur when opening/closing keyboard on device or orientation changes. Without this in the AndroidManifest.xml then everytime a device configuration change occurs your Activity will restart. This is usually not desirable, but is default behavior.