Would it be weird to "ask" stuff over Facebook or text?
If you're going to go asking her out, or asking her if she likes you, through text or Facebook, then don't.
Do it in person. It's more personal and meaningful.
It also means you can see her actual reaction and use that to see if she does like you.
And if she does turn you down, then atleast you're not in the awkward situation of now having to meet her in person for the first-time after being turned down.
You should honestly just ask her. She might not be interested in having a boyfriend though, so keep that in mind.
But there's no point in fawning over her from a distance. You're still in school and you don't want to distract yourself in other places.
You might actually find that having a girlfriend now doesn't do you any good.
Have you talked to your parents at all? They might be able to give you some good advice, even if it's not the sort you want to hear.