The salt damage is easy, most people will agree to it, with the exception of damage to cement or brick, salt is a no no there.
As for trying to not be responisble for slip and falls, good luck. A clause like that isn't even worth the ink it is written with. The Insurance CO, of the property owner is going to say who plows your lot or drive, they say XYZ plowing. Then if you tell them that you have a waver, they are going to still go after you for all you got. Thats why you need insurance.