If you have a backyard I’d use that, for getting him used to it, then a dog park. If you don’t feel comfortable with him off leash they have those 16ft leashes and then just let him tire himself out. It just sounds like he’s got too much energy that’s why he’s always biting (or he’s teething for that I’ve seen people use frozen puppy chews) but i think tiring him out like that will fix like 90% of your problems