A: Yes. But, unless you are going to paint all 6 sides with good exterior paint, i wouldn't use it. I would use something impervious to the weather. Azek or a PVC board.
A: 8" wide is not a precut standard. You'll have to get a 10" board and rip it down. Check with the manager to see if they can get you some. Otherwise, you'll have to find a wood supplier.
A: Yes, it is considered unfinished. Can still be used for regular projects or take stain and paint.
A: Yes, this is unfinished.
A: The actual dimensions are Actual Product Length (ft.) 4 Actual Product Thickness (in.) .5 Actual Product Width (in.) 5.5
A: 1/2 inch thick by 5 1/2 inches wide and 4 feet long. Typical wood dimension nomenclature.