If that cop was involved, then it would be way too stupid for her to talk about knowing anything about the rituals. I'm gonna call it right now; she's gonna be one of the victims of that cult before the end of the case. After all, it's her neighborhood.
As far as the Quinn situation goes, I think that he'll definitely find out enough about Dex to make the connection, but I also think that after Dex came up clean on the Rita thing, his credibility with LaGuarta (sp) is completely shot, and that anything he says about Dex isn't going to be taken seriously.