It isn't designed for that. But you could if you don't need permanence. It could warp and it certainly wouldn't be soundproof. CHECK the thickness of the board vs your intended use. Also depends on how far apart your 2x4 will be.
We did not use ours that way. If you are concerned, paint the BACK and edges of the panels with KILZ. That would seal it from any moisture.
Check SKU #1001218386
Doubtful, but most likely painted
Not sure what I did was took outside corner piece cut it into worked perfect
Yes; that’s what we bought it for.
Used brad nails with mostly success, but a few areas chipped/splintered, especially the ones with a glossier finish. Matching edges is essential, so measure and reinforce the back, or you will see buckling.
Will cut nicely with electric or hand saw. Should paint for a finished look but consider priming if you notice different finishes on the surface (some matte, some glossy).
The 40' wall (=480") is exactly 10 panels long (480/48 = 10) or 15 panels wide (480/32 = 15). The 13' wall (156") is 3.25 panels (156/48 = 3.25) long or 4.875 panels wide (156/32 = 4.875). So you can go with 10 x 5 panels one way or 15 x 3.25 panels the other way. That is 50 panels the first way, or 49 panels the second way. Based on my experience doing our ceiling, I would go with the second way, not only because it is more efficient in your case, but also because it is easier to cut a 32" long straight line than a 48" long straight line. I also want to suggest you get 106 feet of a molding you like and use it to dress the your ceiling - that will hide any slight imperfections in the the fit of the ceiling panels. And before you start, make yourself two T-shaped holders from cheap or used 2x4's to support the panels while you either screw or nail them into place. Cut the long piece of 2x4 about an inch longer than the height of your ceiling and wedge both them under each panel to hold them tightly against the ceiling while you either nail or screw it in place. That will save you some back pain. Being a teacher, I am going to show my work here. First convert the length and width of your ceiling to inches (40' = 480" and 13' = 156") to match up with the units (inches) of the panels.480/48 = 10 and 480/32 = 15, so if attach attach the panels with their long edge parallel to the long edge of the ceiling you will use 10 rows of panels, and if you rotate the panels you will have 15 rows with no cutting. For the width of the roof you have 156/48 = 4.875 or 156/32 = 3.25 which means you will have to cut the final panel in each row. So you can have 10 rows of 5 panels (with 4 inches trimmed of the final panel in each row) or 50 panels. Or you can have 15 rows of 3 and a 1/4 panels, which is 49 panels. Based on what we saw in our house, I would go with the second method, since ceilings are rarely perfectly square, and this should make it easier to do your cuts. Also I would suggest you get some molding (106 ft) to put at the top of the walls, which will hide any imperfect cuts and make the ceiling look more finished. Also, make yourself two T-shaped holders with cheap 2 by 4's to support the panels while you nail or screw them to the existing ceiling. For each T cut the long piece about half an inch longer than height of the ceiling and cut the cross pieces approx. 48 inches long. I hope this helps.
About 2 5/8". From line to line.