Hi Tracy,
Donald's Dining Safari at
Tusker House Restaurant is a lot of fun. Although I have not had lunch there, we have had the breakfast and it was great. My husband and I love that this restaurant offers both African fare and more traditional American fare on the buffet so that we can be adventurous eaters. Our daughter can try new foods, but there will be something for her to eat if she doesn't care for the new tastes.
When we went to Tusker House Restaurant, Mickey Mouse was one of the characters who appeared. Characters who may appear at Donald's Dining Safari include Daisy Duck, Donald Duck, Goofy, and Mickey Mouse. Meeting characters is always fun, and here they are wearing their safari gear. As you mentioned, characters who appear are always subject to change, so Mickey Mouse is not guaranteed to appear, but it is possible.
I hope that this helps to answer your question, Tracy! Have a great time planning your trip, and please do not hesitate to ask if you have any further questions.