My friend has a 1995 Ford F-250 diesel and he want to know how to increase boost.
He's two and like you said he hasn't been taught any proper stud manners. You'll just have to take the time to teach him those manners and the purpose of the stud chain. Work with him everyday, either in a round pen or arena, and be consistent with him. Good luck :)
Seeing as you dont condone violence, continue with the grounding. Ground him for the three weeks as you initially threatened, and condemn him to his room. Ground him for the whole summer if needed. He desperately needs discipline, obviously. Take the games, electronics, any privileges he had before away. Keep him in his room and dont feel bad, he needs to learn. Also, notify your parents if needed. He must learn respect somehow. You will not regret taking his summer away if he acts like this. At some point during this grounding if you do go through with it, sit down with him and have a serious conversation. Get him to talk to you.
Geld him. That's the first step to getting that problem under control. That you would even think of breeding a rank, $75 stud boggles my mind. And, if I'm reading this right, your neighbor drove you home with the pony tied to the back of the truck? Dear God, do I hear banjos playing?