check out organic groups

This is my scenario: Creating a site for a university and need to use Taxonomy to catagorize page content based on College, School,and Department. Each Department and school depending on the college will have their own web masters. I am trying to restrict update,create, delete, list permissions for each user role set in one of these categories. However, when a specific role has a set of permissions in this particular hierarchy, he can still create/edit nodes and assign taxonomies that should not even show in the drop down list based on the permissions set.

Example Taxonomy Tree:

Women's College
-Academics
--School of Arts and Sciences
----Biology
----English
----Math

Graduate College
-Academics
--School of Arts and Sciences
----Chemistry
----Math
----Physics
-Student Life
--Greek Life
--Student Affairs

Example Role Name = Graduate College: Academics: School of Arts and Sciences: Physics (yes the role name will be this long)

As the name suggests, this role will be given permission to edit page nodes but only be able to select the physics category in the list, under the School of Arts and Sciences, which is under Academics, which is under the Graduate college. The user should not see or create/edit in any of the other taxonomy categories in the above hierarchy if they do not have permissions to do so. So the problem is that this user still sees the whole tree, which is incorrect.

My second issue:

If the above role does not have permission to administer taxonomy, even though I have set permissions giving a user in this role ability to create/update access to categories, the user will not see the option to select a category at all.

Please advise If I cant get this scenario to work I may lose client.