I'm pretty sure that much of the room service stuff comes from the Yacht Club Galley. At least, the sandwiches and burgers are from there. We've never gotten any of the larger entrees, and it is POSSIBLE that those come from the Yachtsman - not sure. I am pretty confident that nothing comes from Beaches and Cream. And no, I don't think you can order any of their sundaes.
I think it comes from the Yachtsman--they are the only place that I know of that carries steak and bean soup, which is a regular on the room service menu. Once we brought pretzel bread back from Canada, and ordered steak and bean soup and beer. They laid it out on a linen tablecloth, with wine glasses to pour the beer into. It tasted so good!!