Hi Mike,
There are a number of Disney resort options with kitchen facilities. All of the Disney Vacation Club villa resorts have rooms with full kitchens (1, 2, and 3 bedroom villas) or kitchenettes with a microwave and toaster (studio villas). The villa resorts are Bay Lake Tower at the Contemporary, Grand Floridian, Old Key West, Saratoga Springs, Beach Club, Boardwalk, Wilderness Lodge, and Animal Kingdom Lodge. Of these, Bay Lake Tower, Grand Floridian, and Wilderness Lodge are all quite close to the Magic Kingdom. There are also full kitchens available at the cabins at Fort Wilderness, a quick boat ride from the MK. Additionally, you'll find family suites at the All Star Music and Art of Animation resorts with small kitchenettes. These are usually more affordable than the villas, but they are a bit further away from the parks.
You should know that you can bring your own food into the theme parks, so you won't have to rush off during the day. There are also microwave ovens and toasters available for guest use in the food courts at all the resorts. If you did need to heat something during the day, you'd be welcome to visit, for example, the quick service restaurant at the Contemporary to heat food in their microwave, even if you weren't staying there.
You should also consider contacting the
Special Diets department at Disney World. I don't know the nature of your son's allergies, but the Disney chefs have been able to accommodate many guests with varied food issues over the years. Again, I don't know your son's medical situation, but you may find that the chefs at a few of the restaurants can provide him with safe and fun foods.
Good luck with your planning. Please let us know what else we can do to help.