Yes. Go to System Settings\Memory\Games\(Title Here)\Delete
The installed game should remain on your hard drive, regardless of the Xbox you're using. However, be sure that you are on your own account when you download the game, or you'll have to transfer the content licenses back to your account from your friend's. Check out Xbox's Digital Rights Management page to learn how to transfer the content licenses.
If your 360 drive is flashed then yes you can once the copied game is the same as the game you installed but you could just play from the copied disc.
Yes, all you need to do is install the game on an xbox. Take apart the xbox you installed it on and the disc drive. Run the game and when the disc stops spinning and is running off the hard drive take it out and put it in the other xbox. This works with all games.
Sometimes.
If you're talking about achievements... You can only delete those if you've earned 0 achievement points for the game... Any higher and you cannot... If you're talking about games you installed on the hard drive, you have to go to system settings -> memory -> choose which one you installed the game on -> games -> click the game name -> should be 2GB or higher and should say XBOX 360 game or something similar below that... delete that one because that's the installed game... You can do the same with games you've installed from XBOX Live, as well...
Some Xbox games do work on the 360, while others do not. To check the compatibility of a particular game, see the official compatibility list (see Related Links). To play any Xbox game on your 360, you need a hard drive installed in it.
yes you can play the game without the disc
Yes you can still play games online after they have been installed on the hard drive.
depends on the game, most online multiplayer games DO NOT suggest it.
No, you cannot use an external hard drive on the Xbox 360 to play original Xbox games like Halo 2. The Xbox 360 is backwards compatible with select original Xbox titles, but these games must be installed on the console's internal hard drive or a compatible Xbox 360 hard drive. An external hard drive can be used for storing Xbox 360 games and data, but it won't support original Xbox game playback.
No, however you can buy the game from xbox live marketplace and the game will be on your hard drive
Game information saves on the Xbox's hard drive.