We can spell it however we like but I tend to accentuate the arrrr as the local Thais do. The Thai word is ลาบ which means salad. In this case as you so rightly say, moo is pork. Other meat can be used, e.g. laarb gai (chicken); laarb neua (beef - sometimes raw); laarb pedt (duck); and apparently laarb pla (fish) although I've not come across that.
I find that the main flavour comes from the fish sauce, lime juice, chillis (of course) and particularly the mint leaves. It is very popular in these parts.
The Thai cooks here don't grind or mince the meat but chop in very finely. My wife won't let me use the electric chopper for the meat - it has to be cut by hand. In fact it is unusual that my wife lets me cook this on my own without interfering.
Edit: this is laarb pedt (carry oot from a local restaurant -