Windshield and seat

Ok i have a 80 Polaris and the windshield is all yellow and you can't see thru it. Is there anyway to clean it up. I have tried wax with no luck. If i have to I will by a new one but again its an 80 polaris.... Second question. The seat on this thing needs to be recovered. any hints or secrets on this. My wife was going to get some vinyl and go to town. It doesn't have to be great just usable.

Thanks