qouta and business requirements of even distribution of tasks among employees in different departments having the same role.

extra work items should be distributed to other people who didnt reach their quota that day.

I don't think it makes much sense to limit the number of workitems assigned to a user, what happens in a maverick day where you have x10 the normal load? "Load balancing" the workitems makes more sense (my opinion of course).

The following might be a good read on that:
http://www.k2underground.com/k2/ProjectHome.aspx?ProjectID=99

http://www.k2underground.com/k2/ProjectHome.aspx?ProjectID=37