I really wan't a iPhone, but my parents can't afford to pay AT&T's bill every month. They only stick with T-mobile so I was thinking, maybe I should buy an unlocked iPhone from eBay and use it with my family's data plan. But I have a few questions: 1. What are the pros and cons of buying an unlocked 3Gs? 2.Will I be able to update the new firmwares that come out? 3. Does it have to be jailbroken too? 4. When I buy one and connect it with my iTunes account will it ask for me to activate it or will it automatically lock it?