Another question in addition to my original:

Can the category sidebox:

1) Not show the category if there is 0 product in the category

2) _Only_ show subcategories in the category sidebox. I have two main Categories, we'll call them Cat1 and Cat2. I want to keep them separate. If you are in Cat2, you only see all subcategories under Cat2 in the category box. You would not see anything from Cat1 (not even the name 'Cat1') in the category box.

Please say this is possible with reasonable effort :)