For purposes of calculating "U" values, the "C" factor for 1" gypsum board is 1.2; Resistance "R" for 3/8" board is 0.32; for 1/2" board 0.45; for 5/8" board 0.56; and for 1" board 0.83.

The most time consuming and costly part of installing drywall is the finishing. The goal is to hang the drywall in the best manner possible to reduce the number of joints to finish. Drywall is available in various sizes. The most common are 4'x 8', 10', 12', and 14' sheets. Cost per square foot normally remains constant regardless of sheet size. Another issue to think about is handling and weight. You must consider all factors to decide what will work best for you.

No. In multi-layer systems, the joints and fasteners in the base layers are covered and protected by the overlying layers of gypsum board

Yes, Wallboard that has been soaked by floodwater can be a permanent health hazard. When the wallboard finally dries, there will still be mud and contaminants dried inside and to the wallboard.

Any nail having a length, shank diameter, and head diameter equal to or greater than the dimensions specified for the cooler nail in the system description can be substituted for the cooler nail.

No.

All purpose joint compound with paper or fiberglass tape will meet your needs.

No. Gypsum plaster will not properly bond to wallboard face paper. Gypsum Lath must be utilized when a board product is specified. Gypsum lath has special absorptive face paper designed to permit a strong plaster bond.
Note: Wallboard back paper is not lath face paper. Do not reverse wallboard and plaster backside of wallboard.

Yes, the corner bead should allow enough fill area to finish corners.

Formula to figure amount of material needed to finish drywall is: for each 1000 sq ft of wallboard use 10 gals of premix mud, 370 lf of tape, (also 1000 screws to apply board).