Replying to Friend of a friend. please help!

alright so i know this belongs in LM but i cant use my regular account and i dont have time to wait for an invite. i'm 19, so is she.

so recently my roommates and i have been hanging out with this girl down the hall a lot. real cool, down to earth girl. anyways, she has her best friend from grade school over constantly, and this is the girl i'm into. she struck me as weird at first, she wears this hoody with spikes that she sewed on to the back, but now i can't get her out of my head. she is so fucking funny, no girl has ever made me laugh like she does, and once she started wearing more flattering clothing i realized she is straight up gorgeous. stunning body. we get along really well, and so i decided that my goal is to date this rare specimen of female. but there are obstacles. of course.

1. she sorta has a boyfriend... i mean they're not dating, but i know they would be if not for distance. i think they were kinda like the high school sweethearts, you know? she has made it clear they will be seeing each other over break.
2. she is the best of best friends with the girl on my floor, which has several implications:
a. i'm never alone with her ever. i'm always hanging out with her, the girl on my floor, and my roommates.
b. i might get friend blocked by the girl on my floor. she likes me, so thats not the issue, but i get the feeling she's beginning to see us as a big group of friends... which would be true if not for my predicament.
3. i actually dont want to fuck up the circle of friends either, theyre both cool-ass girls. ideally i'd be dating her and we'd be part of the group as a couple.

so...
1. is this even viable? are my chances of success worth the penalties of failure?
2. how do i initiate it?
a. how the FUCK do i get her alone?
b. how do i... get things rolling? i mean normally i'd just kiss her but this is different, i feel like given the situation i should maybe say something first...? i donno. shit has got me stumped.

thanks NS, i appreciate the help. if i could date this girl i'd be pretty much the happiest man alive, from what ive seen she is perfect for me. try not to be too NSGish, NSG...