Commission Category options

I am new to the Commissions module, and experimenting with how it works to see if my company's overly complex compensation plan can be shoved into the box.

If I am understanding correctly, the only options for categorizing a commission schedule are Item, Class, Location and Department. Further, there is no way to create a hierarcy of multiple categories.

Example 1: I can't assign one % to sales in Class A/Location A and another % to Class A/Location B. Solution: create multiple schedules?

More of a concern is being locked into those categories. My company is a service based organization that pays one commission rate on New subscriptions and a lesser rate on Renewals. We have a custom field called Sales Type. Is there a way for me to cateogorize commissions on the custom field?