I'll tell you what we did with our last collie to give you some ideas.
First though, what are you feeding him? Food can make a massive difference to behaviour in some dogs.
Neutering made no difference whatsoever on our collies energy levels, it did stop all sex related behaviour.
I would take your dog back to dog training. Find a good reward based trainer and take every class you can get to/afford. We did obedience, rally, agility, trick training classes and anything else that came up. Even if your dog is the worse, most embarrassing dog in the class, keep going!
Our collie was 2 years old before he was left unsupervised even for a second. Crate your dog whenever he is left or use a puppy pen (unless he can escape).
Yes you can teach a settle! We had to teach our collie as he was just like your dog. If he does stop and lie down then reward him for it but I'm guessing he doesn't.
Pick a spot, his bed, the sofa, wherever, and ask him to lie down. Reward him. Train it like you would a down stay only it doesn't matter if he moves around as long as he stays in his spot. For example, our collies spot was a chair. I asked him to lie down and rewarded him. Lying down on that chair was more rewarding than anything else in the world. Build up the time between rewards slowly (you might have to start at a treat per second!) and then your distance from him until you are doing whenever you want while your dog is settled and you just randomly give him a treat.
Our last collie had serious health issues and for the last 3 years of his life (from age 2 to 5 years) he had at most one 20 minute walk a day and he was calm in the house so you will get there!
Brain work is for more tiring than exercise so train every day. Use his food so he doesn't get fat.
When out on a walk try incorperating some training. Down at a distance, heelwork, stays, find treat/toy etc.
Remember that your dog is still a puppy and that all the work you put into him will pay off one day!