Tony didn't know anything about Burt's loyalty or murder until Sil told him after the fact. That was all on Sil and his loyalty towards T.

I would say given how long Paulie has been around and what the psychic had to say about "many more" victims hanging around Paulie would have had the biggest body count. He was after all pretty much enforcer/muscle going back to Johnny Boy. He was their go to guy.