To form a question on how to create a double registration system with forms:
Regular User system that only logs and can comments on her notes
Staff member: One created, the staff member should signal/hook programatically created permission and blog space.
How to assign Staff -
Another option is to display additional fields if User selects the Staff choice option... and the pages are then created.
Else, one Staff option is selected, send a box form to specify, why do I wish to enrol. This allows to reduce spam and unwanted staff requests.