Fastpass doesn't play into ticket buying at all. It's a free service inside the parks. Near the entrances to most of the more popular rides are these large rectangular boxes (for lack of a better description) with 2 slots in them. One you stick your park ticket into (you get it back), the other a small rectangular ticket comes out of. This is a fastpass. On it you'll see a 1 hour window that it says to return between (like 11:30-12:30). This is the time you are supposed to come back to ride the ride with a much shorter wait than the standby (regular) line. You are always welcome to use the regular line instead (maybe the wait is under 20 minutes, which is what most of us consider short enough not to use FP or you have plans to be eating or watching a show during the current return window--in either case, don't get a FP--leave them for someone else). You can get more than one FP per day (just look on the bottom of the FP ticket to see when you can get another--it's either about the same time as your return window or 2 hours after you got the one you're holding, whichever comes first), and more than one per ride per day. Just remember, any park ticket you want to use to get a FP, must have been used to get through the park entrance.