There are 5 character meals to pick from:
Goofy's Kitchen, at the DLH is a large buffet for either brunch or dinner. Goofy & Pluto are usually there, as well as a couple more characters (Baloo, Chip, Dale, Minnie, Brer Fox, Alice just to name a few) & sometimes a princess. They do dancing & banging pots thru-out the meal that the kids can go join in. This is really a fun meal!
Surf's Up with Mickey, at the PPH is a smaller buffet, but offers some different food choices. This is the only meal where Mickey is attendance. This is also a great place to see Stitch. We've also seen Pluto, Goofy & Minnie. This is usually a smaller crowd as well, so lots of character interaction. The dance, hula hoop & teach the kids to surf.
Chip-n-Dale's Critter Breakfast, at the GCH is a buffet or order off menu (but menu prices are elevated to cover the character aspect). This is a place to see some of the critter characters you might not otherwise see in the park. We saw Chip, Dale, Brer Fox, Meeko (from Pocahontus) & Kenai (from Brother Bear). The kids got up to play follow the leader during our meal.
Ariel's Grotto, in DCA serves breakfast or lunch (family style serving for at least breakfast....not sure about lunch). This is the Princess meal. You meet Ariel when you go down the stairs. They have a small "royal" program to introduce 4 more princesses. The last time we went they taught the kids to bow & curtsy & to dance.
Minnie & Friends, at the Plaza Inn in DL, is a buffet for breakfast. This is the meal you will see the more "classic" characters. Minnie, Chip, Dale, the Winnie the Pooh characters, Captn Hook, Peter Pan, Alice, characters from Pinocchio, etc. They dance during the meal.
All 5 are wonderful choices & a great way to get some character time. If you're only chosing one or two meals, I'd go with the meals that the characters interest you. Hope that helps!!
You can call 60 days out (actually 2 months out......date for date) ex: July 10th meal you would call on May 10th.
As for gluten free, at each restaurant, ask to speak with the manager & they can go over options. They keep a very large notebook with all food items & their ingredients. If you have other questions or would like to speak to someone prior to your trip.....call Disney Dining & let them know you'd like to speak with a chef regarding food allergies. They will either transfer you to someone or give you a # to call. Allow the chef a week to call you back.