The VX run is open to non VX's. It started as a run to get the noob VXers a chance to see what the VX was capable before hitting runs with all the other Zu's the rest of the week. Size of the group might dictate leaving others behind though. However with that said your friend can always ride along with you for the VX run (if needed) and then wheel his 'migo the rest of the week.
Handheld (FSR) radios are not compatible with CB's...CBs are worth the $$ if you plan on doing any other wheeling. Plus like everyone said it makes the trails more interesting and fun. Most club/groups use them to comunicate.
As far as stock VX's with stock tires... you will see that on a lot of the trails (especially the slickrock trails) street tires will sometimes work better than the off road tires. There will be several stock VX's there. I recommend that if you are new to the off road thing follow another vehicle that is the same as yours and watch the line they take on the obstacle. Those of us with more experience are always more that happy to jump out and spot you. I have yet to see anyone damage their VX's unless they were ,well, doing things to push the upper limits! The VX run is usually pick keeping in mind that there will be new people but with enough difficulty to let you see the capabilities that it posesses.