I found Evolved's essay very helpful and so far very accurate.
I have 9 wrasses (3 Halichoeres, 5 fairies, 1 flasher) I have several shrimp and have had zero problems with them. I would recommend introducing your shrimp before the Halichoeres or at night if you already have the fish in the tank. I also don't think all Halichoeres are created equal when it comes to invert predation. I have Vrolik's, chrysus and claudia and they not only ignore shrimp but the other wrasses, corals and clams.
The only down side for me is they are pod eating machines. I'll never be able to keep a mandarin. Hate that but think it's well worth it as they are beautiful, active and interesting fish.