Welcome to the forums.
1 - Backlight does not turn on for the 7520. Search for and install BBLight, that will help.
2 - No, can't be used as a modem
3 - For games, go to mobile.blackberry.com (from your BB browser).
4 - You need to download the devices OS and install on your PC as well. Use the link in my signature to find it and download it.
5 - Lots. BBLight would be the first you want, then Beyond411, Google Maps, and others. See answer to #3.
6 - There isn't one. You can use the General forum, though