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You worded that really awkwardly man. You tried way too hard. "Hey, I like you, we should go on a real date some time. I'm going to -insert some event or small day trip here-. What do you think?"
Easy as that. You don't have to be gross about it and include that you think she's hot. She doesn't care what you think about her appearance she cares that you like her as a person.
As for your future relationship, I would send a concise apology and include that it won't influence you wanting to be friends with her. This assumes you are actually friends with her. If you've talked like three times and never actually done much together you're probably just fucked for being too antsy, but if you've been doing shit together you can easily dig yourself out by saying something like
"Sorry about last night. I've had tough luck finding interesting girls at this school and I let myself get out of hand. I hope nothing has changed between us. I've enjoyed being your friend."