Hi, I’m in progress renovating my house and I would like to add Xps on outside. My wall will be: 2×4 with roxul comfort bat  –  5×3/4 tongue and groove horizontal sheeting – drain wrap – 1 1/2inch Xps  – 1/2inch strapping – primed 1/2×8 FJ cedar clapboard. My questions are:  1. Do I need vapor barrier on inside        2. Can I attached the clapboard only to furring strips or do I need to reach sheeting or studs    3. Also I was thinking to apply Vycor or similar product on top the furring strips to seal around siding nail but that’s maybe going little to far. I did spend a great deal on research but I didn’t find a specific answer to my exact situation. I live in upstate NY and climate zone is 4 or 5. Any help would be great. Thx