www.sassnet.com
Lot's of helpful folks there.
It's really smart to go to a couple of shoots first and try the various guns out before you invest heavily. Like many hobbies, you can wind up spending a lot of money on CAS. Can't go wrong with a Vaquero as a start. Do the best you can with the clothing at first. You really want to avoid ballcaps, tennis shoes and dress like that if possible.
If you decide to continue, yes you'll need two pistols, a rifle and a shotgun. There's so much gear invoved most people either build or buy a guncart.
Yes, you are right most of the SASS competition is friendly and fun, but there are serious competitors as well. They are called gamers. They are the ones who always have to be in front of you on the highway. Most just sit back and enjoy the shoot and the friendships.
CAS folks are the best. Have fun!