Can the annual pass be added to your room key? If so, what happens at the end of the trip? Does it get reversed out and then added again on our next trip?
You wouldn't want to add the AP to your room key, you want to carry it with you. Disney has been giving 10% off at many Disney locations for about the last year for people with APs. Premium APs get 20%. You need to show the AP to get the discount though.