Re: is he tooo old?
I would insist that you get to know him better. He is about to graduate and guys that age typically have one thing on mind..... If he is 18 and you are under 16 it is leagal to date but you wont beable to kiss him or do anything more. In most states you have to be 16 in order for you to to have any type of sexual relationship, but I think you are still too young for that.
If you were to date make it clear it is just on those terms because if he did care about you then he would understand(for his sake).