Hi Marilyn!
We LOVE Port Orleans - Riverside! It is by far our favorite of the moderate resorts! The food court closes at midnight, but some of the shops inside the food court have varying hours. Some close at 10:00, some 11:00, others midnight--so you should arrive in plenty of time to grab a quick bite.
As you can imagine, Walt Disney World feeds thousands and thousands of guests all day, every day, and they're very adept at providing options for those that have dietary restrictions, allergies, or even intolerances.
Your first step is to email
specialdiets@disneyworld.com. Do this prior to your trip (now would be great!) and they'll get back with you and provide you all sorts of information about Gluten Free (GF)dining. Many of the counter service restaurants do have gluten free breads to prepare things such as hamburgers. Make sure when dining at a counter service location that you specify your needs and ask to speak with a manager. They'll come out and let you know about the GF options and ensure that your food is prepared without cross-contamination. Also make sure that any dining reservations that you book you note that you need GF options. The chef will come out and speak with you about your needs, and work to ensure you are taken care of!
Have a magical vacation!
Amanda