I have had many dogs, different breeds including Foxhounds that are notoriously destructive, and the only times I have had anything chewed indoors is when the dogs have not had enough exercise. I am not talking about a 20 minute walk but a good hour of power walking and off leash running.
By the sounds of it, you have bitten off more than you can chew with this dog. You say he is aggressive and that is easily stopped especially at his age.
He does not need a one on one trainer but should be attending classes with a good trainer in charge that can help you deal with the aggression towards other dogs.
The dog is chewing because he is bored and doesn't have anything to do with his energy.
I have just helped a woman with four rescue Staffordshire Terriers, she couldn't control them on lead let alone off. They chewed, fought other dogs and were generally 100% disobedient. In one walk I had the worse one on a lead walking to heel with no thought of pulling ( in a flat collar) In less than a week I had the owner walking all four without them pulling. In that week I could have all four walking off leash and staying behind me in open ground. In two weeks we were walking her four and my five together, they meet other dogs with no problems, they are sociable to others, both two legged and four. They are also getting at least one good long off the lead walk a day (1 1/2 hrs minimum) these dogs no longer chew because they have utilised their energy.
It all boiled down to the owner being worried about what they might do, the dogs picking up on her worries and behaving to that. Now she is confident, not afraid to boss them and prepared to exercise them as they need they are happy and she is ecstatic.
Get up early and run or walk with him for a good hour, when he is lead obedient exercise him from a bike or on skates. Get some work into him and he will be happier so will you and your family.
Not the dog's fault but yours. Harsh but true.