When you check in, they will offer you different levels of charging privileges. At RPR, we always choose the lowest amount of $100 per day. I can't remember now what the other amounts are. We normally don't carry alot of cash, but do carry enough for some drinks or maybe ice cream. Some of the small vendor carts in the parks only take cash. All counter service will take your key to charge to. We have always been told that you can charge to your room at all restaurants and stores in USF, IOA and at Citywalk. We have never had any problem doing so. Your key can sometimes help you get a table quicker at the restaurants too.
Have fun!!!!!