-You can do it yourself, it's not too hard at all. Two people doesn't hurt though. It's kind of like making a bed.
-Not a high one at all.
-Usually there is a long cable that goes from one end of the cover, under the car, to the other end, which you use to lock it.
-I guess it depends on how big the hail balls are. If they're little things, then probably. But if they're the size of baseballs you'll find dents. Although, I don't think they'd go through the cover and say, through your windshield, so that's a plus, I guess.
-Yeah, you could fold it.