I went not last fall but the fall before with the F-body guy's in my 04' GTO, Saturday morning I got there fairly early, there is a building right as you enter the track that we stopped at to check in, get the numbers for our cars, and some direction as to where to go.
After that I drove up to the staging area I guess you could call it. lots of open parking space for everyone to park their vehicles, trailers, etc. so I claimed my spot, empted everything out of my car (tools, jack, jackstands, spare tire, etc etc) and headed over to the tech area, they checked the car over made sure everything was good to go then checked me off.
You can run in various classes, for anyone with a mostly stock car or anyone who is going for the first time, I would recommend the D class, it is less competitive and for those with stock vehicles and or little experience.
The event I went to was two days, I only raced the first day, each class had 4 x 20 minute sessions or so, I can say by the end of 20 minutes the Brakes were ready to sit, granted that was in a pig of a car reaching much higher speeds than I'll ever hit in my 6 (not sure about the speed6 though).
So all in all you get close to an hour and a half on the track each day, which even one day was amazing, they have defined passing zones, can't pass in the corner and no wheel to wheel racing, if someone flashes you and they are riding your tail you are supposed to move over and lift to let them by, if a corner worker sees you not letting someone by they will flag you to let them by, if you don't they can suspend your day of racing.
Speeds in my GTO in the straits were pushing 130mph, If i would have had better brakes I could have pushed it further yet, I'd say if your planning to do anything to your car before going, bleed the brakes and go with some good synthetic fluid, maybe consider changing the brakes out to a Hawk HPS or one of the other high performance type pads. I brought a set of rotors and pads with when I went incase I cooked mine on the track, but they held up pretty well (that was hawk pads on stock rotors).
Any other questions you guys have let me know and I'll try and answer them, this of course was a little while ago and with a different group, so things may be slightly different. All I can say is everyone should do this at least once in their life, its so much fun.
Wanted to add bring some folding chairs along, everyone kind of chills around their car between sessions (an hour or so) and then everyone gets a lunch break. There is a little town not far that has a subway and a few other food places, or you can bring a grill along and cook out.