Yes, Vantage will have a rating system, but ClassiPress does not have this built in at present. I know of some customers who have used rating plugins in the pre 3.0.5 version of ClassiPress though..
I'm just not sure about it, I don't use the plugin myself. The only reason why it "may" not work with 3.0.5. is because this version uses custom post types. If the plugin doesn't support custom post types then it could be an issue.