I'm not one who would want 4 adults in 1 moderate hotel room. You have the issue of your BIL not being able to share a bed, and those moderate rooms arent exactly spacious.
Will you have a car? If so, you can park right outside your cabin and drive to the parks, eliminating a lot of the transportation issues. Youll probably still have to take a bus to the settlement to get the boat for the MK, but isnt CSR still pretty big and spread out with similar transportation issues? We love the fort and only use disney transportation with no golf carts and really dont find it difficult or too time consuming. I do know that it is a complaint of some though.
As for food, we find being able to cook our own as a nice plus. Planning ahead and if you drive, bringing something like a crock pot can make it a quick job.