mine walk better with a harness because of how it hugs their chest. I am always afraid of collars cuz I'm afraid they will get hung up on something in the house. Mine are trouble makers, well one is.
My tags are on a thingy that I got at Petco that just snaps on. I can just put it on whatever harness I am using.
Dickens' Closet I.D. Tag Holders at PETCO