So I'm a freshman in college, still developing my game. I'm a pretty popular kid, probably one of the most popular freshmen in college. Anyways, today I had a class and since the teacher teaches the same class twice, I went to the session that I do not normally go to. These classes are small btw (around 20-25 ppl).

In the class I usually attend, I'm very outspoken, funny and smart when it comes to answering questions and discussing things in the class. Without being arrogant, I'd say its fairly obvious to everyone in that class that I'm the smartest and most social kid. I'm always talking to the people around me (many of them I've partied with) and I mean I'm a confident guy and I'm sure everyone else can see that. On top of that I always get the highest score on all the tests so people know i'm smart.

So I'm sitting in the class and I didn't really know anyone since it was my first time in that class. A few minutes after I've been sitting there, a girl comes in from the class I usually attend and sits down next to me. In the other class, me and her haven't ever spoken. She kind of sits further away from me and she just never initiated dialog with me and since I'm usually talking to everyone around me, I never really tried to start anything with her. (she's also VERY attractive). I also know that she is alot older than me. I'm thinking she's a senior and she's definitely of age to drink (21). That taken into account, makes another reason I never really spoke to her, as I'd say I was fairly intimidated by her looks and age.
(more in a wow i'm 18 and shes 21+ and hot as shit kind of way)

Anyways she sits next to me, which I originally took as I guess a half IOI since she could have sat next to anyone else in the class and she chose me, despite us never talking before.

Later in the class we had to do group work, so I turned to her told her that she'd be in my group. She agreed and kind of by the way she looked at me I felt another IOI. She also said that the work she did (we were supposed to be looking over our homework with each other) "might not be wrong" or something like that(a little bit of insecurity, intimidation from her?). There was another girl in our group but she was not very talkative and neither of us really payed her any attention. I did use the other girl's work to help make a point about me dreaming of going to Hawaii one day (I figured girls love Hawaii and I said it with some emotion so a little DHV from that?) She seemed to respond positively to my statement by agreeing with me (smiling too).

When she read her homework, she talked about going to Mexico. I corrected/helped her with some things she got wrong while she was reading it. I made the assumption that she went to Mexico for spring break, so I asked her about it and stuff. I was asking her if it was as crazy as it looks on TV and spoke about how its really dangerous there right now. (maybe a DHV since I had alot of knowledge of the situation). She was playing with her hair and her body language definitely gave me the impression she had some kind of interest. After class, on the way out I kind of half held the door for her (I left pretty quickly and she followed) and she gave a very high-voiced thank you. I dont want to say it was intentionally sexy but it was a very sexy kind of voice thank you and she didnt even have to say anything.

Overall from the whole experience, I really felt like she was showing interest. Aside from the physical IOI's, I just had that feeling inside you get when you say "Damn I think this girl is flirting with me".

So I guess what my questions are:
1.) Do you think I'm just over-analyzing and exaggerating the IOI's and she's really just trying to be friendly?
2.) I'm unsure what to do since she's so much older than me. Me being 18 and her 21 means she can legally drink and I can't, so its difficult for me to invite her to alot of things that would be good ice-breakers. ( I love using parties to invite girls I'm interested in to. Easy first date/meeting)
3.) Is it even worth pursuing due to the age difference? I mean even if I did hang out with her, I would have to deal with her friends that would probably be difficult to get approval from cuz of my age. (I'm very confident socially with older people and I know I could eventually get their approval, but I know it would be a difficult task). I guess if I even hooked up with her once it'd be worth it cuz she is very hot. But I really wouldn't mind just forgetting it. I have lots of girls my age that I can get easily and lots of challenges there too.

I guess my biggest thing is confidence with this girl. I flirted with her and stuff and was pretty smooth, but escalating from initial attraction to making my intentions more obvious will be difficult for me. Despite my self-esteem and attributes, I have a hard time seeing what she would be interested in me for. I mean she is very hot (9 maybe higher depending on taste), and I'm sure she gets alot of interest from high value guys her own age. Why would she be interested in someone so much younger?

I want to see what you guys think! I think alot of people could benefit from this because even great young PUA's will experience the confidence drop I got from the age difference. I don't really care too much about getting her (no emotions or pride on the line, just attraction) but I'd love to learn what to do in future cases, the mindset to have, and just basically the best way to approach something like this!

Sorry for the long post...