I have Celiac disease as well, and from my understanding, Disney will accomodate at all their restaurants. When you call to make PS, you can have them mark it on your reservation. Usually, they will give you another number to call, in which you can speak directly with the chef or manager about what meals they can provide for you. All of the restaurants are very aware of Celiac, and can easily accomodate, I think they just appreciate a headups on things. (its so nice to go someplace where its actually heard of!!!)
As far as buffets, the chef will come out and show you which items are safe, and have even made things personally for someone if there arent many options out there. Again, with notice, they can provide gluten free waffles and such.
Disney is a great place for Celiacs, I've found. Unfortunetly, we're also going to Universal and their dining line had never heard of gluten!!! Things will be more difficult there (we actually will just not eat in the park there).
If you have more questions, let me know! I have found info on Celiac boards on this subject, as well, and my mom works in reservations, so I can point you to more info if you need =)