Taxonomy role based access allows you to share and control access to the file plan, the following are the various access roles:Reader: anyone who has access to the SharePoint Site can access the file plan in read only mode, he/she can only see Published versions of the file plan. Reviewer: Assigned through the Admin Webpart, anyone with this role, in addition to what the reader can do, he/she can view and comment on the different elements of a Draft version of the File Plan. Editor: Assigned through the Admin Webpart, anyone with this role, in addition to what the reviewer can do, he/she can add, delete and edit the different elements of the Draft version of the File Plan, and can submit a file plan for approval. Approver: Assigned through the Admin Webpart, anyone with this role, in addition to what the editor can do, he/she can create a new File Plan or add a new version to an existing one, can publish/unpublish the File Plan, and can delete a File Plan. Administrator: Assigned through the Admin Webpart, anyone with this role can manage the access right to the application.

Yes, Taxonomy allows you to import your organization's file plan from excel.

Yes, you can export the file plan, work on it offline and import it back to the system as a new version

You can install the app as may times as you which as long as they are within the same tenant.