You should be able to link the MM to your
MDE account immeidately after purchase. From a computer, scroll over the My Disney Experience, in the Plan and Manage section, click on "My Reservations and Tickets". It'll bring yout to a page with resort, dining, park tickets, etc. At the bottom is your link option.
Anybody on your Friends & Family list will be able to take photos and upload them. Simply find a cast member, take the photos, and scan your Magic Band. The primary user (usually the person who purchases it) will be the only one who can access and download the photos, unless you reassign those rights.