Insulation, Caulk and Drywall

Hey Knightfly... its been a while since I've been here... password troubles!! Stupid thing wouldn't send me my password or let me reset it! :roll: Anyhow, things are rolling right along with the studio and basement construction. I need to post some pictures for some future questions, but I have a few specific questions that I could use your advice on. 1) Right now, the outer walls (by code from when the house was built) have standard "fluffy" insulation with a vapor barrier (visquene (sp?)) over the INSIDE (cold climate) side. I'm considering removing all of this because I have other uses for the insulation and replacing it with rockwool and recovering with the plastic. Is this wise or necessary? I can get rockwool local for about $0.46/sq. ft. 2) The rockwool is thinner than the wall cavity (I think rockwool comes in a 3 inch thickness for a standard 2x4 wall) - should the rockwall be pushed against the inner wall or the outer wall of a two leaf system? 3) I have a drywall contractor who knows how to hang RC channel and is willing to do 2 layers of 5/8 on the whole room with RC-1 on walls and ceiling. Will RC-1 hold that much weight on a ceiling? 4) I contractor for a local hospital *gave* me a case of SC-175 acoustic sealant. I know I will have to order more, but I'm a little confused as to where this needs to be used. Should it literally go around every drywall joint (like corners and between butted up ends of sheets) in place of where drywall compound would normally go? 5) I obviously plan on using it on the bottom of the drywall, but since the RC-1 will hold the drywall out from the stud (as it should), when I put the backer rod in there, I assume I only push that back about halfway the thickness of the drywall and then fill with the caulk? I managed (from the same contractor) to get some generic fire-stop putty for wrapping outlets. I need to take some photos of my ceiling to get advice... There are wires, HVAC runs, holes for showers/tubs above etc... so I'm not sure how best to seal it up. The ceiling itself will be 2 layers of 5/8 screwed into RC-1, which should take care of that leaf, but the leaf that is the sub-floor for the floor above has all kinds of holes in it from HVAC and drains etc. The fun continues!! Thanks for your help! Jim