This will give you a strong, smooth surface. If you have the money to waste, go for it. Diagonal layering may provide the best compromise, but it tends to be a big pain in the ass and a waste of plywood. I suggest putting the surface on so that the grain runs lengthwise on the ramp. You cover more ground going back and forth than you do along the coping, so this should make it nice and fast.
Some people think so.
It is fast and smooth, but those are the only benefits. Rain destroys masonite quickly, so it is usually no good for outdoor ramps. It works OK indoors, but creates a lot of dust when you skate it. Getting that shit in your lungs is really bad for you. Some people swear by masonite, but I avoid it.