Ahhh...
I think there is some sort expen cover you can get, I would put a stop to that bc he could really hurt himself.
The chewing is bc he is still a pup and he is probably teething.
How about getting him a Kong and that should keep him occupied for that little time he is alone
P.S. I had drywall, baseboard and wood door chewers. Their little teeth marks are still there
I use to put clear deordorant on the spots to deter them