Ok, lets try to answer some of these questions
First: If she is looking at you, she is interested in you or something about you. This could be because she's attracted to you, or there is something notably strange about you. If you were heavily peacocked, for whatever reason, people will look at you, but are not necessarily attracted to you
Bus Stop opener... This one takes a lot of skill... Just ask when the next bus comes by. Its natural, clean, and chances are you can keep conversation going from there. No need for some insane routine based opener
As for the other questions, a number close should come naturally if you can hold decent conversation. Try to talk about genuine interests and chances are there will be some reason to meet up in the future
And as for asking her out, this is really up to you. Some guys will preach you have to wait X number of days, I prefer to just casually send a text a couple hours later to keep the interaction fresh in her mind
Oh, and if you ever end up sitting beside her in class and don't know how to open, there's usually one way that is dynamite. If the class is dull, pull out a piece of paper and draw a tick tack toe game. Put in an X and pass it to her. If she doesn't immediately get into the game, just look at her like your confused she's not willing to play.
If she doesn't play, she is clearly boring, hates having fun, and there is no need to waste any more time there
Cheers and good luck mate