Try the lite of SMW, it's actually better than it sounds. EDIT: Puppet War is also good for 2 bucks. It's an arena FPS.
I need a game that's addicting and sorta puzzle-y that has unlimited replayability (game never ends). Is Drop-7 good in that description?
Skate It is pretty fun. My biggest complaint was previously in the tilt and grab controls, but seeing as they've fixed those, go ahead and get it. It's a ton of fun, and second best skating game out there right now (#1 goes to THPS2, still).
No. Performance issues and there are much better RTSs out there. Warfare Incorporated and Red Conquest are my favorites.
I prefer Baseball Superstars 2011, but it's your call. 9 Innings is more realistic and uses a card system, while Baseball Superstars seems to be more focused on an RPG system.