I'm glad you figured out what Drew is allergic to. My daughter just got diagnosed with gluten (wheat/barley/rye) last October. She went to Disney in February and they are great with food allergies. If you send an email to WDW Special Diets at
WDW.Special.Diets@disney.com they will send you a pile of information of what you can eat in each park. The staff at all the restaurants are also very knowledgeable.
I know Drew is younger and it might be easier to jsut bring his food in the park but the info is a great backup. And she swore that the allergin free chicken nuggets were fabulous!
Also for "real life" a good name brand food product for you would be "Enjoy Life". All Enjoy Life foods are specially made to be free of the eight most common allergens. That means they contain NO wheat/gluten, dairy, peanuts, tree nuts, egg, soy, fish or shellfish. It's nice when you can have a "go-to" label. This is their website
http://www.enjoylifefoods.com
Good luck with everything!