more complex read/write access levels

Simple user management in wp is fairly straightforward.

But for this project, I need to make at least 4 different user groups:
– each group can see content from other groups, except one hidden super group
– each group can only edit own content
– public = read only to limited content

problem 1 is that categories in wp seem to have only posts, not pages
problem 2 is that content of some groups needs to be HIDDEN from public, including menu items made invisible

which plugin is suitable? pls only free plugins

In forum of wiki software this type of detailed ACL is piece of cake, so why not in wp?

Tnx for any help !