I used to work in the Back Office of the Front Desk at the All Stars, and the way that the room charging works is that when you check in you can choose if you wan't charging privledges on your room key or not. But they do not preauthorize your card for the amount you are being credited by the resort, instead they run a balance through, usually $1.00 just to make sure that the card is active. Disney will then give you a credit of $500 for the Value Resorts, $1000 for the moderate resorts, and $1500 for the deluxe resorts. Once you are ready to check out or you reach the credit limit Disney has given you, based on the resort your staying at, they will charge the card you placed on file. If you would prefer to pay in cash or by check you can do that as well, you just want to make sure that you stop by your front desk to take care of the bill BEFORE you get to your credit limit, or the NIGHT BEFORE you check out (whichever comes first). Also any time you like you can stop by your front desk and ask for your Folio (technical term for current charges to your room, also includes phone charges and anything you charge to your room) and check that against your reciepts in case you are worried about unauthorized charges.
After working in the Front Desk one of the main benefits I've seen of this service is that if you don't have this service and your credit card is lost or stolen you S.O.L. but if you have this service you can leave your CC locked in your room safe where it is... well safe. Now if you loose your Room Key with charging privledges it is very easy for them to replace that and cancle the charging privledges, access to the room, and tickets on the lost/stolen room key. You don't even have to go back to your resort to have it cancled, you can do it right from any park House Phone by dialing 0 and asking the operator to connect you to your resort. Then when you get back to your resort at the end of the day they can print you a new room key (with valid Photo ID). Also if anything is charged back to your room from the stolen card Disney is usually pretty good about resolving it. You might have to pay for the unauthorized charges for a couple of days, but once they have done their research and find out that it is actually a false charge they will credit you back. Hope that helps to answer some of your questions.