News Blog, Forum and Wiki All-In-One?

I’m starting a project for work that needs to be a WordPress CMS that integrates a news blog, a forum and a wiki (that would be available to desktop computers, as well as mobile and WebKit access).

I would like the functionality to where specific company-internal users can add news items to the blog, or use Share This from other websites to the WordPress news blog, and to the forum; I would like to have anybody able to sign up for the forums, and post under specific forum areas/topics; I would like everything that appears on the news blog and the forum to have wiki links to an internal wiki/document page; finally, I would like this to be accessible on mobile devices.

I know how to do each of these individually using WordPress, save for the forum, but I don’t know how to even start to make a webspace that contains all three..

Should I have multiple installations of WordPress and use subdomains to divide these three areas? Can I do this with WordPress Multisite installation (I have no experience here)? Is there a way to make all three work in the same environment as a Super Admin?

Any help or guidance would be most appreciated.