Clearly if you get QJs or KJs in late position with callers you should stay in, but what about with 1 or 2 people already in there? What guidelines do you use to determine when to play and when to throw them away? Typically if I'm in LP with only one caller I'll raise it, but in MP I'll dump it. With any more than 1 caller I have to be more careful.

Also, how do you play Axs in mid/late position with no callers?

There have been varying arguments to Ax suited's merits. I will raise it first in when x = anything from CO or Button, but ahead of tha I usually toss it unless x > 7 as I don't think its good enough to be played.