Cwood, one thing I neglected to mention is that the Tomball Gun Club is a private range; not normally open to the public. They open it up to us,I am not a member) when there is a match held there. They hold both registered Benchrest matches,NBRSA group matches) and club matches. The club matches are score matches and much less formal. Still as competitive, just a little more laid back. Probably the best place to answer some of your Benchrest,note the capital "B") questions is to go to http://benchrest.com/ and browse that whole site. There is mirads of information about organizations, classes, rifles, match types, neck sizes, etc. More info that you can absorb in a short time. However, to answer some of your questions.
In pointblank Benchrest,registered competition at 100, 200 and occassionally 300 yards) there are really four classes of rifles.
1. A sporter rifle - maximum weight 10.5 lbs, caliber 6mm or larger, stock foreend not more than 3" wide.
2. A light varmint rifle - maximum weight 10.5 lbs, any caliber, stock foreend not more than 3" wide.
3. A heavy varmint rifle - maximum weight 13.5 lbs, any caliber, stock foreend not more than 3" wide.
4. unlimited rifle, basically must be safe. :>)) Most of these are rail guns.
There are more stock specifications for the first three classes above dealing with minimum drop of the heel. You have to read the rules a few times to understand them but what you have to know is that lots of the long range style stocks will not work because the buttstock bottom and the foreend bottom are much too parallel to meet the short range rules. Mr. Shehane makes great stocks but he is mostly a long range shooter and so are most of his stocks. I am not bad-mouthing him as I have a couple of his stocks and like them but they are on long range style rifles.
Now, the other thing that will help you is to know that you can always shoot up in class in Benchrest. That is, you can shoot your Sporter in the sporter class, the light varmint class, the heavy varmint class, and even in the unlimited class if you so desire. That is why you will see people recommending you build a 6ppc as your first rifle. You can shoot it competitively in all the classes. However, if you build a heavy varmint rifle, in registered competition, then you are limited to the heavy varmint class and the unlimited class if you so desire to shoot there.
On Neck sizes. Many years ago when the PPC cartridge is developed, the brass they used was bad enough that they had to turn the stuff down to around .260 - .261,combined total of the bullet diameter and two neck wall thicknesses) before it yould clean up and be uniform in thickness all the way around. Many reamers, chambers, dies, etc. were developed around these dimensions and are still used by many shooters today. However, the brass quality is much better and you do not have to turn the necks that thin to work. So, many folks today develop their program around a larger neck size such as .269. They have to turn less material off, necks are more durable, etc. Both lines of thought on neck thickness are used successfully today.
Again, I would urge you to come out to the Tomball club match, look around, ask questions; better even yet, bring your rifle out and have a good time. If you are like me, you will see more there than you can absorb.
Joe