Well, there's a plausible out for the one girl, considering that the explanation given for it leaking to the other girl was that you decided to ask your questions during a study hall, a time when gossip-mongers and other assorted types are known to have their ears open for anything juicy.
So I'd give it a few days and then exert caution in where and when you have conversations that you don't want to get eavesdropped in on. I suppose at that point you might let slip a bit of a noticeable lie in order to see if it'll spread and come back to you, but I wouldn't recommend that strategy in general and have no idea how to formulate one that would be easily recognizable and serve the purpose.
For your own well-being though, I'd recommend giving her the benefit of at least some doubt.
As for your friend that you're crushing on, well, it sounds like he doesn't really reciprocate, though, really, there's a whole number of factors that could be at play here. The key to watch for here is how he treats you from this point forward. More thoughts and perspective on the matter and how to go about gauging where you stand and what if anything you can/should do could be rustled up
here though, as they've experienced it all, pretty much.