Drywall and Caulking Questions

I have a bunch of drywall and caulking questions that I could not find the answers to in the reference section or in my searches and other reading. If any of these have been answered elsewhere please forgive me for missing it. Pointing me to the relevant thread would be much appreciated. 1) Can anyone tell me how much Acoustic Caulk is typically used in the seam of a 2 sheets of 5/8ths sheetrock wall? Does someone have an ounces-of-caulk-per-seam-foot approximation? I assume from what I read here that with two 5/8 sheetrock on the walls ceiling zig-zagged I will be using 3 beads on every seam (with 3/8 backing rod). Or is it two beads in front of each rod? I am trying to estimate my Acoustic Caulk purchasing needs up front because ContractorsToolSupply.com is offering free shipping on everything through the end of the month and I know shipping can add a lot to the cost of this stuff. In a similar vein how much putty is needed per outlet box? I see Metacaulk Putty Sticks sold in 18 cu. in. packages but I have no idea how much coverage I'll get with that. 2) In Rod's book on page 67 he shows adding mass to an existing deck (ceiling). He shows that the added drywall is caulked (I presume with acoustic caulk) at the edges, but I don't understand what air passage this caulk is preventing. Is this only useful if you fully caulk every joist? Or is it intended in case a joist has a seam of OSB running above it? What about the perpendicular OSB seams? If I want to just add some mass but will not cover all of the existing deck is the caulk useful/necessary? Would just gluing whatever spare material I have around (without caulk) still be effective in adding mass? Is caulking all joists recommended even if you don't add mass? 3) Can blueboard and skimcoat plaster be used instead of regular sheetrock and mud? Would one use mud anyway to seal the flat seams and skimcoat over that? Any special considerations at the ceiling and corners? Should the first layer of sheetrock be regular with mud and green glue and only the top layer be blueboard? Thanks!

Small tube 10 oz.= 25 linear feet for a 1/4"x1/4" bead 1/4" x 1/2" bead = 12.5 LF One gallon = 300 linear feet at 1/4"x1/4" and so on ...... add in 10% loss and another 10% for wider or deeper caulk joints And yes one bead and backer rod per layer. I lost count at 200, 10oz. tubes :shock: That was interior and exterior Peace Tom

Thanks Tom!