For the study group idea, where would it take place? If at all possible, I'd try to have it at your place. This way she can see some of your interests from the books that you read, movies, music, how you've decorated your place, etc, and thereby giving you something else in common. So if she ends up liking the same types of movies or music, whatever, you have a perfect excuse for inviting her to do something with just you next time with whatever you have in common. "Oh hey, there's a kick ass band that sounds just like XXX that's playing on Saturday, you wanna check it out with me?"

If it's in the library or some place else pretty neutral, bring your music player. Ideally a CD player so you can sprawl some of the CD cases around the study area so she can't help but pick some up and check them out. Course, the pretense is that you got there early and decided to listen to some tunes while you were waiting for them. Although if she's smart then she might be into mp3 players too.

While you're there anyway studying, it still would be fine to just ask her if she and friend would like to check out a coffee shop/some sort of event on the weekend. As long as it's some sort of social event and you've got other people with you, it's not going to be obvious.

I hope that my advice was somewhat helpful to you. I tell you, it fucking sucks trying to figure out if someone is gay and is interested in you in that way. Good luck girl!