1. ClassiPress itself doesn't have an import tool, but you can import xml files via WordPress. I am also aware from mention in a thread of a customer who has had success with importing a csv file using a particular plugin
http://www.csv2post.com/ (this has not been tested by the development team however, just the 1 customer).
2. There are a list of recommended and tested plugins on our
resources page, and any plugins outside of this are really up to the individual to try out. I know many of them do work fine, but some just aren't compatable - much like you may get with any WordPress theme.
3. Not currently. Support comes in via these forums.
4. No
5. There is only one option for featured ads at present, and that is an additional charge which runs the same duration of the ad. At present there is no option to charge based on number of photos. Users can use embedded Youtube videos, but cannot upload video files. You can run numerous ad packages based on duration and price, or you can charge price per category. There may be enhancements to this in a future release, and these may be based on customer feedback as to what sort of feature requests are made.
6. The ClassiPress Admin options allow you to place ads at the footer of the ads or in the header spot. If you wanted to have ads per category this would involve some customization of the theme.
Ultimately if the theme doesn't have all the features you're looking for, you could always look at a coder for hire who could add the enhancements. The theme is not encrypted, allowing customers to customize it to suit their needs.