1. No, ads are not deleted but are sent back to draft status once an ad expires (so yes, they would have to be manually deleted by Admin). From an
SEO perspective a lot of people wouldn't want their ads to be deleted, so what you do with this would be up to you.
2. Yes, users can renew their ads if this is a setting you have allowed in the ClassiPress admin options.
3. For this you could create a "wanted" category and use a custom ad form relevant to this specific category.. You may want to do some additional customization if you wanted things displayed differently somehow though.
4. I would have to check this with the development team as we haven't yet had confirmation of upcoming features for the next release.
5. Yes. There is a "Price Per catagory" option currently available.