Desserts
Chocolate - cake, cookies
Cheese
Fireworks Show
No idea, but it won't be the holiday one. I think it will just be the regular one. So you will want to make sure you book the Fantasmic Dessert package for the show before the fireworks
Seats
Either the front row or the back row (where your kids can stand up on their chairs if necessary)
Check-in
One member of your family will want to be at the podium at least one hour before the appointed check-in time (at least). One time, we were there 1.5 hours before the appointed check-in time and there were already 4 people ahead of us.
Note, they check-in for both shows at the same time but try to segregate.
After checking in, you have guaranteed seats so you are free to do other things. They don't start seating until 1/2 an hour before the show. Be sure to bring a plastic bag to hold your dessert box. The last time I went and wanted to bring the leftovers home, the lid kept on coming off so had to hold it with both hands in front of me.