Beginner question: upload file extension?

I’m planning a WP site that’s a large community site. There are about 10 distinct major areas of the site, each with their own administrators who manage their own pages. The WP is hosted by me on a dedicated server.

Is there an extension that allows for “idiot-proof” uploading of files by admins? These admins frequently have to post MP3’s, PDF’s, XLS’s, and such things for the community. Some of the admins are not that computer-savvy so I don’t want to get into FTP. I’d really like a one-click web interface from their admin areas of WP by which they can upload any files they want, then be able to integrate them easily from their areas in the WP site.

Furthermore, one specific page on the WP site will be a collection of nothing but MP3’s. And another page will be a collection of nothing but PDF’s. (A long list of everything that’s been uploaded.) Is there a way in WP to set up a page which simply looks in a particular directory and lists all the files available in it, so that users of the site can browse the list and download the ones they want?