Workspace Access to Export but not access to other projects

I am struggling with the project and workspace access for my employees. This is the situation:

• I want to give Project Managers access to export the schedule (need Workspace access)
• I want to give superintendents access to see Tasks in their ipad (need Workspace Access)
• I do not want Project Managers to have access to ALL the projects under a workspace, I want them to only have access to the project they are assigned to. (Need to remove workspaces access)

Help! I am not sure how to resolve this. Currently my PM's have access to all projects in a workspace cause I can't figure out how to limit to project only access without preventing them from being able to use the export and ipad tools.