Personal user contributed content

Hey everyone, I am new to WordPress, but love it. I am also new to forums, if you are reading this I already thank you for being willing to help others out.

I have not really searched the forum for my answer to this basically because I do not know what terms to use in a search.

Situation: I work for a company that rules, policies, and procedures change depending on location. I want to create my site to have the common rules, but let users add more as they need.

What I need is to know how I can achieve the following (if even possible):
I would like users to be able to log in, see all the information and posts I have put on the site, but also be able to click “add” and create their own categories, subjects, or add their own notes. I would really like there to be an option to add their own private or public notes. Using a form I have set up, I would like the information inputted to directly go to the website for that user (or their group).

Is this even possible? Basically I think what I want is to design a good website (wordpress) but have some functions as a wiki page (with the exception being it would be private or public to the user).

If any additional info is needed please let me know, or if there is an alternative to this too. (the regular comment box probably won’t cut it for what I need, but maybe there is something else.) Even keywords that would help my google research would be greatly appreciated.
Thanks,