That age difference isn't bad at all. I was really scared man, scaaaared.
She was replying to you with a text message: in my experience, I just want to get the message out in as little space as possible. If it had been me, I'd have sent a '1'. Which means "Yes motherfucker, I got your message. Why the fuck is a dude text messaging me?" Don't fucking text message me. Exclamations mean I'm excited. Yes, that kind.

Next time you're sitting together, just ask her if you can put your head in her lap. When she inevitably says yes, tell her how smelly she is. That'll keep her on her toes.
Brig should NEVER drink.
Seriously, sounds like she's not looking for anything lasting. Which is supported by the (girls are trouble) and the fact that she's gotten with two of her brother's friends. Put it down like a playa, throw some strength in to your pimp hand, hit it and forget it.