1 - Yes, you can find the theme documentation
here (although you cannot access the full page unless you are logged in as a customer). This includes information for configuration of the theme including some video tutorials. For anything else you are unsure of, the forums are here of course :)
2 - No, the currency is not selected by the ad poster, it is set by the admin from the back end, as shown on the ClassiPress admin demo
here.