Think of it like this....."conditioned" and "un-conditioned". In a perfect world, your insulation separates the two. Limiting condensation caused by sweating. The vapor barrier always goes on the conditioned side of the insulation. Think about "craft-faced" Owens Corning fiberglass insulation. The paper or "Craft-face" goes toward the room.
Any punctures or holes in the VB is a potential for moisture problems. I was taught to be anal when sealing any and all holes/penetrations in the VB. I mentioned Tyvek tape because it's common. There's a bunch more. The tape is plastic, water can't penetrate. Hope I helped.
