I'm confused - and a current AT&T customer who is eligible for upgrade. It looks like there are four ways to buy an iPhone? (1) at Apple Retail Store (2) at AT&T Retail Store (3) Start process on Apple Store [on-line] and pick up at Apple Retail Store, or (4) Start process on AT&T Web site and pick up at AT&T store. Is one choice better than another? Also, for either method starting with the on-line process (ATT or Apple) is there a way to change your current phone number instead of keeping the same one? Also: can I keep my current (air force) discount [FAN?]. I've read postings with all sorts of different answers. Thanks!