-I'd say he's an adult or almost one now.
-If he hasn't started spraying by now, he might never start unless you get a new pet or he smells another bunny. He could also start for no reason at some point. If he's neutered, he'll probably never spray.
-A sturdy cardboard box (no tape, staples, etc.) is a great toy for jumping. I also highly recommend the Maze Haven, which is sold on this website.
-As long as he's not actually swallowing the plastic, it's fine if he chews on it. I guess you could cover it with cardboard or try using lemon juice on it if you really don't want him to chew it. Also, you shouldn't be using any litter/bedding besides towels or rugs outside of the litter box - it makes litter training a lot harder.
-That's normal. One of my bunnies did that before I got him a bonded friend. He's just really affectionate.
If you ever get another bunny and bond them, he'll probably stop licking so much. It's certainly not a problem, though.