Instructable similar

I would like to develop a tutorial posting site with similar characteristics of those of instructables site Basically the idea is to have user profiles where others can follow them (like in twitter) to receive notifications of new tutorials developed by that user, rates, stats, private message them, etc. Also the site will need to be able to upload text, images and videos with 1 step per page, have a menu bar to explore all the steps and select either one of them or click on the next button to go 1 by 1, have related tutorials on one side, info and stats of the poster, etc. Please refer to instructables site if any doubt about the scope. Thanks.