Nice to see a newb post like this asking the various questions that many of us take for granted as common knowledge.
First off OE-R lifters do not have anywhere near the amount of preload that stock lifters have. Stock replacement lifters (LS7) would be better. Because of the preload difference OE-R's are known as loud and annoying lifters. They don't give you any advantages over stock except helping you to empty your wallet faster.
To replace lifters, you would take off the alternator, upper intake manifold, lower intake manifold, valve covers, coil pack bracket, rocker arms (requires new bolts), lifter retaining piece
Hopefully your socket set has deep six point sockets in it. You will want to ensure for tools you have the following.
Sockets, deep or shallow
7mm
8mm
3/8"
Sockets Deep
10mm
13mm
15mm
Ratchet
Magnet
Metric wrench set
3" and 6" extensions
Ability to torque at 87inch lbs and 15ft lbs
Pick or small screwdriver
It would be good for you to find the youtube video of doing a lower intake gasket or maybe it was rockers. You'd be doing all that except not removing the springs until you went with rockers down the road.
