Yes, uncheck the "overwrite final results" action on all User Roles
Yes, please read on for instructions
Right click the 'Outcomes' grid > 'Clear this result' or use the Bulk menu
Enter results for all units and the enrolment withdrawn date
3 different ways to result a client
Yes, you need to have the "search for existing unit results" option ticked when enrolling
It means no students have completed the course