i have a hill in my backyard, and just a gues is that its 10 feet tall, and it gives me alot of speed, enough to come close on backflips off a jump, but its pretty steep, so if its steep, you'll get a ton of speed
if it gets that cold it might, i never hit mine if its below zero, but iv used HDPE for rails, and that works good, and you can use that no matter how cold it gets
i don't know if five feet will be enough speed, and one foot wide might be kinda hard to walk up, so i would just use a ladder and make the down ramp part 3 feet wide, and that tower wont hold unless you put in more supports, but other then that very good.
chipboard is cheaper, but plywood is better, iv made one and i used plywood, and it worked good, i would suggest plywood because chipboard isn't even that much cheaper and plywood is better
it should work good, i have a five foot tall one with a ladder on the back and like a 50 or so degree ramp,so like the same as yours, and it works good
it was 6 inches wide, i attached the topsheet by pre-drilling holes about halfway through the HDPE, then used 1 and a 1/2 inch screws to screw it on, and to get the sheets flush i just lined the up the sheets and screwed them down thight, but also rubbed the edge with my ski edge to get rid of...