RE: Need some help with Twist Rate!!!!
Unless you need/want to shoot bullets heavier than 60 grains or so, the 1:12 twist is probably ideal for just about all bullets in the 50 to 55 grain range. These are overwhelmingly the best varmint bullets, so for a varmint rifle that is what I would pick. For the regular 52 gr. Sierra HPBT only, a 1:14 should be adequate but somewhat limiting. The 9" twist allows you to do shoot varmints as well as do some long range match shooting.
Barrel length: at least 20" but not over 24" - 22" would be about ideal in my book.