Classifieds application on Facebook

Our company needs a classifieds system inside Facebook. We have no experience on working with Facebook applications, so we would need a freelancer who can give us some knowledge and develop the system for us. We want an application inside Facebook, where users can post ads related to our market. All ads are going to be free to post. Some features we want: • Facebook users can post ads. • Ads need a title and a general description of the item. • We would need to be able to register some categories and sub-categories so users posting ads can choose from. • Allow control of HTML on the ad. • Ads would need to be approved by our administrator before being posted on the application • A number of fields on the ad that we still need to defined (like company website, etc) • Uploading of images on the ad. • Filtering ads by cities and region • Ads would have an expiration date • People interested on an ad would need to be able to contact the ad poster • Admins can (optionally) be notified of expiring ads • Price field for ads, so users can search for prices too • Users can edit or delete their own ad postings • Admins can edit or delete any ads • Commenting section inside every ad • Users can flag ads for inappropriate content • Users can browse through the categories and sub-categories and see the ads on it • Regions Control (allows you to restrict viewing of ads based on locale, so users don't see items they aren't physically near them, also allows customization of the region types, such as village, borough, etc) Any other feature the bidder can suggest us would be greatly appreciated. Bidder would have to have good design skills, but we can work togheter on that since we have designers and programmers. The app would also need to have a website interface, so users can go to our URL and see ads posted on facebook. Please send bids with a good portfolio of facebook apps.