I would expect pre-orders to start at the same time for Apple, ATT and Verizon. I have a FAN discount and have ordered from Apple in the past so I am not sure why you cannot order from Apple that it must be from the premier site?
Maybe others can shed some light.
For service or support questions including existing order status, call: Customer Support: 1-800-331-0500
Information on iPhone unlocking can be found here by copying this link into your browser: https://www.att.com/deviceunlock/client/en_US/
I think all that you would need to do in order to purchase the iPhone from Apple would be to provide them with your FAN number. My Hospital has a FAN account with AT&T and I am able to upgrade from Apple or AT&T.