Hey first of all, see if her body language means anything to you. If she's especially being shy around you or if she's smiling a lot, etc. Those are some of the things that might tip you off that she might just like you. Since she is a shy girl, you should start making the first move and start talking to her more and get really friendly. To answer your third question, if all does go well and you've begun dating her, it wouldn't be a bad thing. Your ex-girlfriend was the one who dumped you, I assume. You're entitled to your own happiness, so if this new girl makes you happy - go for it.
Good luck
