For rock your going to want a rear locker at a minimum that's selectible
What? Why would you say that? Respectfully, have you ever run a spool or automatic locker in the rear that would qualify you to give this advice?
OP, you don't
need a locker at all, and you definitely don't want one right now. Wheeling your truck open/open for a while will give you time to learn how to pick a line correctly, and then when you do add a locker of some sort you'll really be kicking ass. If you add a locker right away it'll be a crutch and you won't be as good in the long run. I do run an automatic in the rear, and I've run it since shortly after I started wheeling, and I'm definitely not as good a wheeler because of it.
Procomp stuff is ok, but it's not the best out there, or even among the better stuff. It's 4WheelParts house brand, and 4WheelParts is kinda the WalMart of the four wheeling scene. The guys I know that run Procomp tires say they last a while but are noisy and don't hook up well anywhere except mud - that's because they have a very hard tread compound, and that hard compound won't do well on the rocks you want to crawl over. I'd go for a mainstream brand - Goodyear, Falken, Cooper, BFG, General, all make great AT tires. Check out the reviews on Discounttiredirect.com and Tirerack.com then pick one that fits your budget.
I highly recommend OME shocks for a truck that sees a combination of road and rocks. They ride firm on the street and are like butter when you get on the dirt. They're great. Check out Toyteclifts.com.
Good idea to join a 4WD club. They'll show you the ropes.