Multiple levels of authority and access

I would like to use Drupal to create a site that has multiple levels of authority and access, depending on the group that the user is in.

The authority would go..

Admin
Employee
Group
--Group Admin
----Group User
Anonymous

The Admin has all the authority and can go anywhere and view anything and they can create accounts and assign them to any Group as well as create any type of content.
The Employee can do the same things as the Admin, just not update the sites modules, and other bits, but they can create any type of content and create any user and assign them to specific Groups.

Then there will be an unlimited amount of Groups that can be created. Each Group will be composed of a Group Admin and Group Users

The Group Admin can create users, but only assign them to their specific Group. They create content, but that content is only viewable by the people in their Group (and up), and they can moderate any and all content created within their Group.

Group Users can create content for their Group, and put in revisions, but they have to be approved, either by the Group Admin or by an Employee or the Admin.

Is this feasible? I am looking at maybe dropping back to Drupal 5.7 for this if the Organic Groups is the way to go for it. I want to make it as simple a process to set up Groups, Group Admins and Group Users as possible, since I will not be the one moderating the site after a while.

Is it possible to do this with Taxonomy Access Control?

Did I give enough information? I am proficient in PHP and MySQL as well as the HTMLs, so setting up forms and doing database queries isn't an issue.

Thanks,

Tim