Hi again,
- To post an ad needs registration. And it makes sense, otherwise for sure some people will forget to write their email and the problems will beginn. The owner can not be found and so on. But if you insist to have this working you will need some code modifications.
- Yes, he can. When you click on an ad the ad description will open. On that site is a contact-form (second tab on the side) that can be used to send a email directly to the ad owner.
Regarding a discount you can check this site:
http://www.appthemes.com/resources/wordpress-hosting/
If you have further questions about discounts, you may contact appthemes directly:
http://www.appthemes.com/about/contact-form/
Cheers