What do you pay upfront to be in this program? What happens if I end up wanting to keep the phone instead of getting the 'iPhone 13', keep making payments until paid in full? Once in the program and you decide 12 months later you want new phone at launch, do you just preorder like everyone else?
IIRC, what you pay up front is the tax amount on the phone and one month's payment, but don't quote me on that! If you want to keep the phone, just keep paying it off until you get to 24 months, then the phone is yours. If you do opt for a new phone, you get a new loan. If you return the old phone, the old loan closes, which is how returning the old phone is optional. You probably could just pay off the loan in bulk and then sell the phone, too, I suppose. If you do return it, Apple ships you a box and instructions for resetting it.
Yes, I did get pre-approval like everyone else through the app and will pre-order through the app at the same time as everyone else but IUP members see a different purchase flow that indicates we are buying as part of the upgrade plan. Whether or not there's actually any material difference behind the scenes is unknown. Do IUP members have different device allocation? No idea. Perhaps others know.
