I'd see her smoking as a bigger issue than her past to be honest.
I mean what is the problem? She got her baps out and had a few photos taken - many women have pictures of their baps somewhere on the internet.
It's not like she's asking you to propose to her, just go on a few dates and if you like her it will stop being an issue, if you're not that fussed then that's that.
If her smoking really makes you uncomfortable though, you should probably just end it.