onasled, aren't you at newyorkmini.org? Or maybe I've seen you on NAM....Anyway, CCM (Cape Cod MINI) gave you a link to some of the threads of some of the track days that have been done by local message board participants.
I recently joined the BMWCCA and was assigned to my local chapter. I have yet to do a HPDE (High Performance Driver's Ed) with them. However, I have done 19 track days with 6 different groups. I sometimes came across and/or was instructed by instructors who also instructed for their own BMWCCA region as well as that of whichever club's event I was attending. I have met some of the Boston and White Mountain chapter instructors (among others) while they were instructing for SCDA at New Hampshire International Speedway(NHIS). They were all excellent. BMWCCAs in general, have an excellent reputation for their HPDEs.
CCM gave a couple of groups that I second. SCDA,
www.scda1.com is excellent. I ran one event with COMSCC at the end of the season and was impressed with their organization, as well. Most of the participants had excellent track manners. I would definitely run with them again.
www.comscc.org
Another excellent group is NASA-VA. Very consistent and high quality instruction on track and in the classroom.
www.nasaracing.net I've done Summit Point and VIR with them.
If you've never done any "performance" driving in the past, I wouldn't worry about doing anything to your car. Learn the car as it is. Then you can make changes. Many, myself included, have even done a number of track days on run-flats. In the beginning it doesn't matter as much.
A helmet, as mentioned, would be about the only thing required. Snell M or SA 95 is usually what's required. If you're buying new, you'll end up with a Snell 2000. Helmets fit differently, just like shoes, so I'd try to get an opportunity to try some on before purchasing. I purchased mine at the pro shop at Lime Rock. I later looked online and may have been able to save $50, but at least I had help in getting the right fit.
Every event that I've been to except one, I already knew that there was going to be at least one of my MINI buddies in attendance. A couple of events that I attended last spring and summer, we had close to 20 MINIs, many of the drivers already knew each other. We've been having a blast.
We've shared food, beverages, rooms, tarps, shelters, tools and lots of laughs! CCM let me use his wheels one time (he was on dedicated track tires). I've given away an extra set of partially used front brake pads so that someone could get home. It all works out, like the fellow with the gasoline explained.
You'll have a blast, hope to see you out there next year!!