What is a polite way to ignore this guy or tell him to leave me alone? Also, what are his feelings about me?

It honestly sounds like he's just trying to pull something on you. I'd do something that embarres him in front of a lot of people that he's trying to impress (his prep friends). Someone like him makes a sport out of going after someone like you just to get at you, and the best thing to make him stop is drag him down and make him look really bad in front of people. If he stops messing with you, you know he was messing with you. If he persists, maybe he really does like you, but you would need to tell him that he's creeping you out and you need way more space than he has offered to you.