Is there individual access control for each staff member or can multiple staff members access the same account?

Your kitchen staff can access the Kitchen Prep and Expedite Screens with one account. Multiple sign-ins are permitted.

To allow/restrict KDS access to staff members:

Step 1: Visit Setup > Staff. 
Step 2: Under Staff Roles select the role for which you want to make changes to.
Step 3: Click on Edit Role.
Step 4: Below POS Access check/uncheck View KDS.