The behaviour you describe...the sneaking up on your and surprising you with attacks is the same behaviour you should be using on this roo, if you want him to remain on your place. Get yourself a rooster stick...it should be long and lightweight. Every time....and I mean every time...during the training phase, carry your roo stick...make sure the kids do also.
Never let this roo rest when you are in the coop or hen yard. Surprise him when he comes out of the coop and touch him with the stick, right on the back or under the tail feathers. If he shows fight, lunge at him and whop him good. Never let him eat or breed while you are there....whop him good on the butt if he attempts it. Every once in awhile, lie in wait for him to come out or in the coop door and scare him with a lunge and a tap with the stick.
No need to yell or chase....top roos don't have to make any noise and they usually don't have to chase much after they have made their point.
If you are walking by him and he doesn't make a wide berth around your advance, lunge and attack with your roo stick. The object of these lessons is to make this roo very nervous....so nervous that he won't dare enter your space. You are big and he is little. You have a stick and he has measly feet/spurs and a beak. You have the power of life or death and he needs to know it....RIGHT NOW AND EVERY DAY. Be consistent.
These lessons should not have to last very long before your roo understands that the humans, no matter if they are big or little, have the upper hand. They are the boss roos. Even if he starts behaving and leaves you alone, remember to surprise him with a lunge or a loft kick to his rear now and again. Boss roos never miss a chance to school a lesser roo...this keeps their position in the pecking order. If he stares at you, whack him with the stick. If he doesn't get out of the way when you walk towards him, lunge and attack.
I have even gone so far as to go in the coop after dark and knock an aggressive roo off his preferred spot, just so he doesn't get comfortable with his place on the roosts.
Sound mean? Not really. Its the only thing they understand and its natural to them. It shouldn't take longer than a few days or up to a week of this type of schooling to improve your roo's disposition. If it does not, he is too stupid to learn and he needs eliminated from your flock gene pool. You really don't want stupid AND aggressive in your flock, do you?
Try it...its fun and educational!