Key cards are used to get in and out of the room and to charge purchases to the room. Some guests also use them to gain access to the parks.
As members of a Disney Convention, we had 3-day Park-Hopper tickets which allowed us to go into multiple parks per day for a total of three days. As often occurs, we didn't use the full capabilities of the passes, only visiting one park on Tuesday, and then not entering the parks again during the visit.
The Disney Photo Pass has no up-front expense. There are Disney photographers all over the place. They are happy to take your picture and then attach it, electronically, to the Photo Pass. Later, with-in 30 days, from your own computer you can access all of the photos taken during your time at WDW. While you can't freely download, all of your pictures are available for purchase. The Disney Gift card is available to add to your available funds. We received a pair from the tournament director, and three more from the Disney Vacation Club.
The Pre-departure Timeline