We recently added a second level to our home, which resulted in our brick-faced chimney extending through this space and out the roof. The chimney encloses two flue pipes for our furnace and fireplace, and runs up, along an exterior wall, but in the interior space. The brick work is not decorative in the least, and therefore will be hidden with a stud wall and drywall. My issue is that I've got the framing for this wall up and insulated using unfaced fiberglass batting along with a plastic vapor barrier. Now however, I'm noticing moisture collecting on the vapor barrier in this area, as I've determined the bricks give off just a little bit of heat, which is enough to cause condensation to collect. The second level is currently unheated, and in Northern MN, it's not terribly warm this time of year, which likely isn't helping matters any. Any ideas on how I can properly correct this so I don't end up with moisture/mold growing behind the drywall once it's up? Would using rigid foam insulation make any difference, or will the same issues crop up? Thanks for any insight you may be able to offer!

Getting ready to do first drywall project and will start with a small closet which is just under 4' square. It's about 44.5" one direction and 46" the other. I've read that it's preferable to hang drywall horizontally for strength, but also to try and minimize seams. For this closet, does it make the most sense to just stand the sheets on end, trim off the couple inches from one side and let the rock span the full width of the wall? That would give me seams only in the corners and at the ceiling. If the above is the way to go (vs horizontally), will it be difficult to end up with sloped edge of the drywall running vertically in the corners?