Relationship/friendship adivice?

Hi guys, this is a throw away. Now why I am asking WSO for advice over reddit eg is because I feel you guys are more like myself and can relate far better then typical reddit users and plus most of WSO are well over my age and have had experience relationship issues. I haven't built up the courage to ask my friends or family about this. I don't have a father figure or role model on the scene to ask for relationship advice.

So setting the scene, I am close to finishing my studies in high school (17), I am single right now. However I can't help but think my best friends girlfriend likes me, to be honest I like her too. Awkward one.. My best friend used to live in town until he moved about 3 hours away, in a different state. They see each other on average once every 3 weeks whilst doing their last years of school. I also think my best friend is doing some suspect things with a girl (Don't think its cheating but still very odd) and his girlfriend is.

I will give some examples when she has maybe given me singles or what ever

So it started here, about 3 months ago, all three of us (me, my best friend and his gf) went to a college open day. I felt like I was talking more to my best friends girlfriend then he was. At this point I didn't like her and I didn't like third wheeling and tried to give them space. My best friends gf lives close to me and we get the same train home together after it finishes. When they say goodbye they don't even hug, thought that was weird, but didnt think much of it. We get on the train and talk for the whole train ride (an hour and a half). She asked me really personal questions like if I liked anyone and asked what I thought about a chick who liked me, this caught me off guard and she asked about my family. I didn't think much of this, however I started to have a crush on her.

We go to the same school if I didnt make this clear enough. In one of my classes she starts sitting next to me and leaves her friends. I started to think more about this. We talk a lot and laugh a lot and she complements me (she said she learns a lot from me since I always openly express my opinion on things with teachers and also said I was extremely intelligent and wanted to know more about Hedge Funds since thats what I told her what I want to do) Then over the duration of 3 months and now she has been starting to seriously tease me and joke around a lot more, with some pretty brutal stuff. I cant tell if this is flirting or not. She is typically a very reserved girl who doesn't talk or laugh a lot with people. She usually texts me first wanting help for school then we end up keep texting and talking about other stuff. Finally she likes everything I share on facebook and she posted a photo I sent to my best friend like 12 months ago on my timeline.

I think I might like this girl enough to jeopardise my friendship with my best friend tbh.

So WSO I have three questions.

Firstly. Do you think she likes me (relationship wise) , and if so how much? Enough for me to work with to tempt her away from her bf?

Secondly. What would you do in my position? pursue the girl but maybe put the friendship on the rocks or wait it out till they break up or back off completely?

Finally. How can I tempt her away from her BF who is being a bit of a dick to her and doing stuff with other chicks? what tatics should I use?

Thanks for your time and interested to hear what your $0.02 are.
Best