Being honest some of your openers aren't that bad and in fact I may even steal one or two of them!
The perving one is good.
Also if she gives you a somewhat prolonged look, smile. She will react in two ways:
1. Look away.
2. Smile back, but it will be reflective. The shyer your smile, the shyer hers will be, the more confident it is, often hers will also reflect it (bear in mind some girls are shy btw so this isn't a guarantee, but she may still give you a shy smile)
Oh and btw her lingering, it could be a sign of her wanting you to talk to her but really I wouldn't worry whether it is or isn't. If you keep seeing her, here's one I tried and got an e-mail for (after a conversation): "Are you following me? 'Cause the last thing I need right now is another stalker!"
(it turned out she was on the same course as me at my uni. Haha. We saw eachother around a bit after that but all we did was say Hi and have brief chats. We weren't really that bothered with eachother in the long run)