What privilege is required to edit a resource?
I mean to even load the editing page, and not get "You are not authorized to access this area of the system."
Whare is this determined? Is it the highest privilege required to edit any of the fields, or is it set somehow else?
If you haven't already, it may be helpful to read the 'Permissions Help' that can be located under Help / Collection Administration Help / Permissions and Access Control.
In order to see the EditResource page, a user must satisfy the Editing permissions for the relevant Schema. These permissions can be customized to suit your workflow. In a default installation that has not been customized, Master Resource Administrator will allow a user to see EditResource for every resource and Personal Resource Administrator will allow a user to see EditResource for any resource where that user is in the 'Added By Id' field.
After that, it is up to the permissions set on the individual fields, which again can be customized to suit your workflow.
So, I need to go through every field and change permissions? Or I can change the schema?
Quoting from the mentioned help page, "The schema permissions establish minimum requirements that apply to all fields. Field permissions can be used to provide additional restrictions for specific fields beyond what the schema requires. Note that for each field, CWIS first evaluates the schema permissions and only if those requirements are satisfied does it proceed to check the field permissions."
For fields that specify no requirements beyond the schema permissions, it would be sufficient just to edit the schema permissions. For fields with additional permission requirements, it may be necessary to edit them as well depending on what the requirements are.
I can't really answer in more detail without knowing how your permissions are configured.
Could you describe the kind of workflow that you want to implement? If I knew what your goal was, I might be able to suggest an approach to reaching it.