[janko10]

1. Installing things on WM is the same as regular windows. Installing and uninstalling LOTS of stuff will eventually leave some registry entries here and there, but you can always hard-reset if it gets too cluttered, messed up. I'd install whatever you want and just see how it goes. Uninstalling fixes lots of issues just like regular windows, but not always.

2. WM does not have a bulit in backup program. You can backup your contacts easily with Outlook and 'copy' your SD card to your harddrive but that's about it. You can try a ton of different programs like SPB Backup or Sprite that will back everything up.

3. To be honest, the forums here are a great souce of general info, just use the search. Also look at forums.xda-developers.com