Good Day, I'm building a directory style website

Good Day,

I'm building a directory style website http://www.wikidwell.com. We now need to extend the site with multi-vendor ecommerce functionality.

Currently listings can be submitted from the front end once a user logs in but there is no front end editing of the listing item which we also require.

I am looking for advice, ideas on the best solution for adding this functionality. The theme is currently running on the genesis framework.