A:
You would have to meet the clearance specs of 2 inches top and sides and 4 inches rear. Even then, I would make sure there was a vent hole at the rear of the cabinet in line with the fan on each unit. If you left the door on the cabinet I would also provide a vent of some sort to allow room air to flow in.
The 2" clearance spec would preclude stacking these one on top of the other. I would also be concerned about the weight of a fully loaded unit sitting on top of another unit. I built a shelf unit for the 3 units I plan to have. With proper clearance for air flow the top of the top unit is about 4 feet off the floor.