Performance Management

Hi All, Client's requirement in Annual Performance review is to make the Performance Rating uneditable for Managers once they fill in their Ratings and HR Specialist can edit the ratings. To be precise requirements are :

1. Manager can not edit Performance rating once they have provided/saved the worker's rating. (Read only access to managers for Perf Rating however they can edit and update the comments underneath)
2. Manager should not Submit Performance Document of the Worker (Hidden Submit using EL Expression)
3. HR person can edit the performance rating once Line Manager Saves/provides Rating. (HR people completes the Calibration)
   
   It would be of great help if any one provide some insight. Thanks