I feel a bit of a loser posting this, but the anonymous function helps nicely

I just want a bit of advice and encouragement - if I ask a girl out (I've known her, and talked to her on/off for a few months, but recently developed a massive crush on her [first thing I think of when I wake up or go to sleep kinda thing].
Anyway, I've never acted on my crushes before, but this feels right - I think she might/probably will say yes if I ask her out for a drink, but to make sure it isn't awkward or rehearsed, I have a couple of questions

Is it best to say to her that I really like her ("I really like you, and I wanted to ask you blah") or just ask her straight out, skipping that part.
Chances are I'll see her next in person (haven't got her phone or MSN), waiting for the bus, so would it be best to ask her out then, or to ask her for her phone number (how?).
I know it sounds odd, but I'll panic over the small details, and forget the big picture if I don't have things sorted in my head before I ask her.
Ta
