if exposed to direct sunlight the plumbers pipe(white) will break down quicker than the electrical(grey). However I assume You will still use plumbing fittings which although the two will work together, the fit isnt perfect and they are still made of the same materials as the white pvc. if you are worried about the pipe failing you could always go with schedule 80, its a much thicker walled conduit and will outlast you and me.

Set up some sawhorses and a sheet of plywood. Set the blade just a hair deeper than the panel. With the panel on the plywood, have a helper help hold it down tight and cut. Dont try to cut an end that is flopping as it will crack. You can cut multiple sheets at a time layered on top one another as long as you keep it held down tight to the ply.

anti hotspot tape is the usual way to do it, it helps with abrasion too.

Looks really good and likely easier to clean than wood. I also like that you painted the interior of the doors and the bottom of the sink black. I, too, have a stainless steel sink (which I like) but I failed to realize that the black stuff that is on the bottom of each bowl sheds off if not painted. Ended up spraying clear spray paint on it after it was installed. Also like the idea of the battery powered "closet" light on the right side.