Mindfield; Okay, sorry to be blunt, but, you asked for advice.
An 18 year-old and a 14 year-old are WRONG. Doesn't matter whether it's legal, doesn't matter whether all you want is a non-physical relationship for now, it's not healthy - for you or her.
You will be having your first real emotional experience with a child - yes, we've all heard the 'she's mature for her age' line before, and it wasn't convincing then; 14 year-olds are 14 year-olds.
Every male on this site will tell you growing up as a JW emotionally retards you. I swear, when I left the Borg at 27, I had an emotional age of about 16. So, the fact you are attracted to a kid does make sense. Think about that. In your next (and that's about a 99.999% chance given how ill-starred this is) relationship, you will go through shit adjusting to a real woman... or be so stunted that you will seek out teenage girls as you can't cope with a mature woman.
Don't think it happens? Read up on some case studies.
She, on the other hand, when she should be having relationships with boys around her age, will be having a realtionship with you. Almost a man. Not what she needs.
You write the legal age of consent "...is 14. So theoretically, we could engage in... sexual... contact. But I think I'll wait a little for that."
Okay, take the next thing I say in the general "yes, adolescent girls can be engaging and cute, it's not peverted to think that" way - I don't think you're a pervert. But that SOUNDED SO PERVY!! So, what first? A little webcam action with your FOURTEEN YEAR OLD honey? Sorry to be gross, but you've got to THINK about what you're doing! You may have convinced yourself it's not your crotch talking, but I don't think you've convinced many others.
For god's sake, go out and get the book 'Lolita' by Nabakov, and watch 'Pretty Baby' (tacky '70's film with Brooke Shields). Both are about older men fixating on younger girls. Oh, 'Paper Moon' and 'Leon' have the same theme, but subtler.
Now, you're still a teenager, but if you can read those books and feel that having even a non-physical relationship is not tacky, unhealthy, and possibly even exploitative on you part (whether you want it to be or not), then... well, I still disagree with you.
But I think after going through that book and those films, you won't need to be told it is wrong. Think up a 14 year-old daughter of your own, and imagine this obviously horny 18 year-old telling you he just wants a non-physical relationship with your daughter, and imagine how you would feel, and you won't even have to get the book or watch the films.
Again, I stress, you're not a pervert. I snogged a girl at a club once. Thought she was 19-20. Met up with her the following Monday. She was wearing school uniform, for the good reason she was 15 and at school. Now, I could have argued "she's no virgin, she's slept with half-a-dozen people already". I could have argued "she's cute as a button and willing". I could have said "well, she's mature, and 16 in a few months". I didn't. I confess they went through my mind, but I said no. It would have been so TACKY to do anything else.