ServiceDesk 7.5.1 Security Permissions

I am trying to find the proper mix of permissions to allow some of our advanced HelpDesk users to be able to do the following: 1) Bulk Close Incidents, 2) Create, Modify & Delete SubTasks and 3) Create, Modify & Delete items in the Incident Classification Trees.  I have tried several iterations of adding permissions to a new group, adding some of the permissions from the OOB Admin group permissions, but have failed at finding the exact ones I need.  if anyone out there has setup a group similar to this I would appreciate an info you have on this.

Thank You