When I was doing student teaching, the high school I was assigned to was right next to a middle school, with the athletic facilities in the middle.  Essentially, it was one big campus of kids grades 6-12.
12th graders dated 6th graders -- sometimes.
12th graders dated 7th graders -- often.
12th graders dated 8th graders -- frequently.
12th graders dated 9th graders -- commonly.
If you put kids together who are of an age to have romantic feelings, they will do so, and age is not that much of a natural barrier.  The barrier is more in our minds, a taboo.  That's one aspect of this, and on that level, Motyracy, I say if you're in the same school, be friends; it's no big deal at all.
Now, physiologically.  These days, in our well-fed parts of the globe, kids eleven years old have become parents.  I read of a case in the Pacific Northwest where a 9yo boy got a 14yo girl pregnant.  Puberty no longer waits until 13 to begin -- so at 14, a boy almost certainly has some substantial hair, and the developments that go with it.  He is capable of being aroused, and does so, and most likely manages those by himself frequently.
BUT he hasn't been at it for long!  At 18, Moty, you've had four more years at handling the new chemicals happily rearranging your body, and the urges, passions, etc. that go along with.  He is in a much more explosive condition; something that to you is now no big deal could set him aflame in a moment;and since individuals are all different, even though you two have a lot of common ground, you have no idea what might turn him on.  So on that level, a warning:  you could be playing with fir; in fact probably so.
Another physiological note (anyone with more knowledge feel free to correct me):  from a scientific article I read a while back, the 18yo brain is actually in a greater state of disarray than the 14yo one, becaasue the younger one is just getting to work on it, really.  You know how at a construction site, when things are getting close to a finish, there can be stuff everywhere and it looks like chaos and like nothing will ever get completed?  Think of the late-teen brain the same way.  And there's a big caution, if this holds true for the two of you (depends on your own personal biological progress rates):  YOU may be less capable of making judgements than he, in moments of passion/horniness!  So, another warning.
I didn't see in here what state you're from, but note this:  in some states, even a serious kiss will get you labeled a sex offender.  It wouldn't matter if the minor bribed you to go with him, drugged you to get control, knocked you out, and tied you down and then planted a kiss on you that you didn't want; under most sex-offender laws, the minor cannot possibly be at fault, so the adult always is -- irrelevant of actual circumstances.  So depending on the state you live in, you could spend the rest of your life viewed the same way as a multiple raper of elementary school children; all it would take is a moment of yielding to an intense impulse, him getting upset, telling his mom, his mom calling a family services counselor, who is required to report it to the cops... and they will write the event the way that will make them look the best, and get them credit toward raises and promotions; since the law doesn't care about truth, they won't either, and you will be required to assent to whatever they've written, if convicted.
Don't scoff at that, BTW -- I know a guy whose GF was 17 when he turned 21.  She bought him beer 

, got him buzzed and happy, stripped, and gave herself to him for a present (I've talked to him, her, her sister, and his mom, and the accounts match well).  Her mom got a hint of it -- she wasn't sure, but still she called the cops.  He took a plea bargain.  And now he's stuck for the rest of his life with having to hold to the official version that he bought her alcohol to get her drunk, hit her and knocked her down, tore her clothes off her, and raped her.
If it sounds like I'm trying to scare you -- you got it.  I am.
You're not a pedophile, not if he's got pubic hair.  He might be a "child"; that's a tough call, and depends on who's doing the defining -- but if it's some sort of children's services, he is.  If you're at the same school, he's a peer, essentially.  So there's nothing creepy, or anything like that.  What there is, is danger -- low probability, but VERY potent, life-destroying danger.
So in the end, I say be a friend, but don't let out a hint of anything sexual; don't even tell sexual jokes, prolly don't even laugh much if he tells any.  Don't touch him, though don't dodge away if he touches you in any innocent way.
And find someone less risky for your crush to land on.