Developer for wordpress - repost 2

I have 2 site's with word press site on it that i would like users to register so they can edit the themes and try out what templates that would like to buy, This site must be unhackable and reset every 3-4 hours to the original theme with only the info i supply them on how to edit sites, so they should only be able to add plugins and not mess with the ones that are already installed, The other site where the templates are showcased that they can purchase and download in .zip form for a fee and will be sent to there email address, The .zip files will have to be uploaded to a shopper press site and prepared for sale, As well capture emails through pop up and given 7 free E books when they leave there email and name, With these two sites they must be linked, Clients or customers must have a very good walk through on how to edit and change themes as well as easy steps to purchase, Hosting and domain name registration will be used through my affiliates only. There will probably be long term support for the right team.