Re: camp club
Each Passport America campground has different restrictions. Most don't accept it when there is a big annual event. Some don't accept it on certain days, many limit the usage to a few nights. The restrictions will be listed in the entry for each campground in the book or on the CD or at the website.
Most campgrounds like reservations but a few will not take them (or will not take them from Passport America members). Many do not require a credit card, and those you can cancel or change even the same day. The ones which take a credit card during the reservation process will tell you what the timetable/cost is to cancel/change the reservation.
I would say that I usually pay between 10 and 16 dollars a night. The parks tend to be cheaper and more conveniant in the southwest than in the north east (where the land is more crowded, naturally, and costs more and is further away from where you want to be). Carry some cash, some parks accept plastic; some don't. Some parks are pretty cheezy, some are average and some are really nice.