Build an Online Store

Hi, I am looking for an experienced web developer who is able to do the following: Create a custom theme that can be used with Wordpress, and someone who is willing to support theme updates if it breaks with a new Wordpress update. I need an eCommerce system designed that will allow me to upload digital files, from movies to photos, which will then be automatically categorised, and the relevant details page shown afterwards where the relevant details can be filled out. Users should be able to join and upload content. I want to be able to take commission on every sale. The developer must also be willing to provide support for 3 months after completion. I want the site theme to be unique.