I have lots of WoW questions..?

First off, try both, and see which one you like more. Warlocks have higher survivability, but mages do more damage and are (in my opinion) more fun. For your gear, if you are going to pvp get stam/crit/resil gear. PVP gear doesn't translate well to raiding (resil doesn't matter in raiding) and a raid guild will not take you seriously in nothing but PvP gear so i would build 2 sets. You can wear your gear anytime, any piece, but with the way Blizz screwed up the definition of "epic" don't necessarily think purple is spectacular gear.