Tomorrow I'm going to be purchasing an iPhone 5s at my local Apple store. I've owned iPhones in the past, but I've gotten them all via AT&T stores. I have a few questions before I go tomorrow morning: 1. I'm currently an AT&T customer, but not the primary account holder. However, I am an authorized user on the account. Is this fine for performing an upgrade? 2. How long do I have to return the phone and get my upgrade back? (AT&T) 3. Can I split the cost of the phone and use two different payment methods in the store? (Ex: Credit Card and Bank Card, or Credit Card and cash) 4. I know exactly the model I want, who do I talk with to buy the phone? Just go up to an employee that isn't busy and tell them I want to buy a phone? 5. Is any additional info I need to perform the upgrade? AT&T Account # or something? Or do I just give them my phone #? How does this work? Thank you!