Others will chime in with more, but you get bands for "free" with your resort stay ("free" as in you don't have to pay any additional fee...you paid for them by paying to stay at Fort). At the Fort, you will use them for comfort station access, and you COULD use them to purchase IF you decided you wanted to link a credit card to them. IF you were going to the parks, they would be used for Fast Passes and gate admission and once again to pay IF you linked a credit card to them..... obviously that is not applicable to you. There are customizable and decorated magic bands available for purchase (I think $20+, but don't quote me) for those that want more than the basic magic band that all resort guests get for "free". Others can offer more and better detail about other things they are used from for ( I think it also does some stuff with photo pass and is also part of some of the interactions at certain attractions i.e.: test track), but at this late hour I can at least get you started with you will get bands but you DO NOT have to pay any extra for them. Have a great stay!
Oh yeah, yes you can just use regular credit card for purchases.