Hi Staci,
Wow you are going to have a packed vacation! You are definitely going to want to make Advanced Dining Reservations to dine at any of these locations. You can go online here or you can call Disney Dining at 407-WDW-DINE to make your reservations. Here is a
link to all character dining.
The reservation you will have the most trouble making will be at Cinderella's Royal Table. This restaurant traditionally fills up when the 180 day booking window opens however you can always take a chance. For dining with the princesses, you can head to Akershus in Norway or 1900 Park Fare for dinner with Cinderella and her family.
For Pooh and Friends, Crystal Palace in the Magic Kingdom is your only option. The characters appear throughout all three meals so pick the time that works best for you.
For Mickey and friends, there is the classic Chef Mickey's in the Contemporary but I really enjoy breakfast in Tusker House with these characters at Animal Kingdom. Goofy hosts a breakfast at Cape May Cafe in the Yacht Club and Lilo and Stitch make tonga toast a delicious morning meal at Ohana in the Polynesian.
You can always see characters throughout the parks as well but I love scheduling downtime for a meal and getting personalized time with the characters as well.
Have a magical trip!
Beth