I'm sure a bit of dry paint wont hurt your rabbit, although keep a close eye on him, if he starts to look lethargic, and stops eating/drinking, or pooing, you should contact your vet, a temporary break in eating might not sound serious but for rabbits it is as their digestive tracks are designed to keep moving
As for stopping chewing, I don't have much to suggest except maybe a fireguard, there are chew stopping sprays but they don't always work for rabbits and they might mark your wall, and make sure the rabbit has plenty of distractions, unlimited hay to chew on, maybe some wood toys, maybe consider getting your rabbit a companion, rabbits are great together when bonded properly and he probably wont be as bored and feel the need to be destructive