Thanks Eric.
I was able to successfully check for Membership status, and i also finally figured out how to set the CatID as a session variable. But now I'm struggling with how to define the discount itself. In the Discount section of the eCart object I can check for memberStatus = 1 AND CatID = 12 (for example), but then when i apply the flat-fee discount of $20 it only does it once, whereas it should be multiplied by the number of CatID=12 items present in the cart. How do i write that up?