% Comp checkbox improvement

Our team would like to have the following options for the %comp checkbox.

• The checkbox can't be checked until the required deliverable (such as, attachment, URL links) are added.  Use case: there are some tasks that we would require user to attach file or add a URL link before they can mark the task completed. 
• The checkbox can't be checked until the user provide the "cause of delay" if the actual end date is beyond the the planned end date. Also, the "cause of delay" can be displayed as in a column in the task list view. Use case: in the current version, user can close a delayed task without provided a reason. We would like to have the user to provide the "cause of delay" as mandatory action. 
• Once checkbox is checked, regular user (such as, task owner) can't no longer make changes to the task, and only the super user (such as, PM or admin) can reopen the task for editing.  User case: in the current version, task owner can uncheck the % comp checkbox and start making changes to the task again. PM would like this option for better auditing purpose.