A lot of good information on the TORCS site -
http://www.torcsracing.com and on the TORCS forum on the "TON" -
http://www.texasoffroad.net/forum/ubbthreads.php/forums/143/1/Texas_Off_Road_Championship_Se
The courses this year have been all off-road (hare scrambles), no moto-cross or enduro-cross sections. The loop is between 5-7 miles and each (adult) class races for 70 minutes. There are multiple classes on course at the same time, each class leaving the start in 1 minute intervals. Usually a dead engine start. The website has the schedule of when each race starts and the order of the individual classes. Everything so far this year has been pretty mild, course-wise. If there is a hard section there is usually an easier (longer though) option. Nothing dangerous except maybe some low tree branches. The October round is at a new property so I have no knowledge of course conditions, although if it's part of the SHNF then it will probably be sandy, no? Courses have been well marked with ribbons, arrows, X's, etc.
There is a practice session each day and you should be able to get in at least two practice laps. There are C and D classes both days but the course is generally less beat-up on Saturday since the C and D classes run before the A/B and Pros. Plus, the C and D classes race in the afternoon on Saturday is that's a plus. There is a fee to enter the property, normally $10 per person, with discounts for kids and seniors. You'll get a wrist band that you'll need to put on before practice. I think the normal race price is $40 (?) but there is a discount for members who pre-register. There's usually not long lines at the sign up trailer except for the first round. I belive they take credit cards and you will have to sign a waiver to race.
They will require you either rent or purchase a transponder for the day. I think it's $10 to rent and $40 to buy(?). I bought mine in 2007 and still use it today. They'll give you pre-printed, vinyl, temporary numbers at sign up unless you want to join and then can run your own numbers (if not already taken and there are some other considerations regarding number of digits, background colors, etc). You'll also be given colored, paper "dots" to put on your bike and helmet to denote which class you're in.
The D class is for true off-road beginners. If you have some off-road experience then they'll suggest the C class, either based on bike size or age classification.
The races are organized and run well. Jackie and Gil do an excellent job as do all the other volunteers - scorers, the sign up crew, course marshalls and sweeps. I've been racing with them since 2006 and try to make at least a couple rounds a year.
As far as bike prep - plan on fuel for at least 20 miles (plus practice), hand guards are a good idea and you'll need the aformentioned transponder which you can tape, ziptie or stick to your front fender. Some guys even carry it in a camelbak or zip tie it to their chest protectors. Some racers install pull straps on handelbars or rear subframes to help in case they get stuck. Some people slime their tires in case of flats. Almost everyone runs with some sort of hydration pack - highly recommended. If you're riding a 2T carry a spark plug and wrench with you just in case.
The biggest thing is to just have fun. You'll find pretty much everyone is laid back and enjoying themselves, people generally move over for you (as long as they're not in your class) and most will slow down or stop and ask if you're okay if you have a problem during the race.
If you've got access to a '91 or older bike come race the Double Decade class with us - it's a blast!
Good luck and I hope you have a good time.