I suppose I could add a 3rd point:
3) If having multiple groups, using an expression to assign a task to a group could be problematic, eg assigning to "group(Payroll)". Which group should it be assigned to if there are two "Payroll" groups.
the jbpm identity module is good for demo and small companies. It is better to implement your own custom identity module that provides the functionality you require. So:
1) not supported by jbpm (or use departmental pre-/postfixes)
2) Again... not supported unless..... (see 1)
3) Again... not supported unless..... (see 2)
For now, we have decided to use pre-fixes for our departmental type groups etc, so we will never have a group with the same name.
This will work fine until we develop our own identity module.
Thanks for the input, Ronald.