I need to build a site with roughly 70 users than can only edit their own portfolio page(s) and 1 to 5 users that can edit every page.

the 70 users need to be very limited to what they can do. No changing the layout or design, only posting content. the content needs to be displayed in a smart and beautiful way that is hard for the user to mess up. The content they need to be able to post is pictures, video, and audio. the video and audio files can just be URL link that automatically generates a player.

basically I need to give 70 people a site more or less like a cargocollective.com portfolio site, and a few admins to rule them all.

am I barking up the correct tree with concrete5, and how big is this tree?