Another thing that might be useful to you is the Guidebook for Disabilities. There is one for each park and you can pick them up at Guest Services, where you can buy tickets or usually at your resort if you are staying at WDW.
The Guidebooks don't have a lot of information about boarding the rides that would be useful, but they do list a little bit about each ride, so you can figure out if it's a quiet boat ride or a turbulant thrill ride. It also lists things like loud noises, dark rides and flashing lights. This might seem like a strange suggestion, but look for the rides/attractions that say they are not recommended for guide dogs/service animals. Those rides tend to be the ones that have loud noises, bright or flashing lights, jerky motions, which are probably things your friend would want to avoid.