Definitely discourage him from chewing on things he shouldn't. With Max, I always diverted him to playing with his soft toys and he still likes chewing on those. I sew our own indestructible toys from a tightly woven poly/cotton blend.
For the growling, I bet he is just playing. Max did that when we played fetch. He also liked to attack my feet in the morning, nibbling at my toes. I taught him that he couldn't do that. I would say "no bite" and put him back in his pen while brushed my teeth. He learned that if he wanted his freedom, he couldn't attack my toes.
Be matter of fact in your corrections, not angry. He will learn.
