Typically, the Pocono events are under sold, so it's virtually unlimited track time. You can probably easily get 100 track miles. I easily blast through a full tank of gas - so you definitely want to fill up before you arrive. At Pocono, there's hardly any wait to get on the track, so there's no running in assigned groups.
Lime Rock sells out fairly quickly - so sign up as soon as you can if you want to go. They limit it to about 70 drivers. (By contrast, Pocono usually attracts about 40 or so. We really marketed the sh*t out of one of the Pocono events last year and got about 60 people.) Anyway, Lime Rock is run in groups. I think about 4 of them. Each group gets 20 minute runs (or maybe 30, I forget), and then the next group goes out. Then it recycles.
At both LRP and Pocono, there are timed laps in the afternoon as part of the competition. We get two timed laps. So, there's a warm up lap, two flying start timed laps, and then a cool down lap. That takes an hour or so, with typically three cars (staggered) running at the same time. After the timed laps, there's usually some time left for more untimed lapping. At the end of the day, there's a trophy presentation.
Some people (myself included) have Hot Lap timers, so we can get our times during practice as well. Highly recommended if you end up being a repeat customer. It's nice to see how your driving changes effect your times.
The hotel at Pocono is cheap, with blocked out CART rooms at $55/night. Pocono is quite safe - at least the infield. nothing to hit if you go off course. Oh, btw, at Pocono we don't run the entire tri-oval. We get a corner (hence the North course and South course, etc.) So we're on the main track for the banked corner, and then you dive down into the infield "road course," before spilling out onto the main track again.
In terms of track time, Pocono is the best bang for the buck. If it's your first track event, I would highly recommend doing Pocono first to get a feel for what it's like. Lime Rock can be extremely intimidating for a novice who's never done a track event - especially when you have some dude in a WRX STi or Vette riding your butt in the no-passing zones. Plus Lime Rock is NOT a safe track in terms of the things you can hit if you mess up. I've done Lime Rock three times, and each time there has been cars towed home - plus people can and have been killed at LR. I have yet to see an accident at Pocono that resulted in a dent.
Same helmet rules apply. If you're a novice, by all means go to CART's website and look at the rules. Novices have to do certain things, like have a big letter N on the back of their car. I would also tell CART you're a novice when you register. Novices also have to get driven around a few laps (this means someone driving your car) at the beginning of the day. Not a big deal and a good way to learn the line.
Lastly, and I don't mean any disrespect at all, but these are not drifting events. I promise you, if someone showed up thinkg otherwise, they would be asked to leave immediately - and not with their entry fee. And as B pointed out, they're not races either. There are restricted passing zones (on the straights; NOT on the corners). When someone does something stupid, or is driving way too recklessly, they get black flagged and talked to.
on the gas thing 
