Hello,
I've seen some of the Excellent reverts here from the experts -
I would also like to add that It's be better if you use either Dimension Or Item Attribute Category rather than going for Custom Fields.
Since every time you design a report - you'll have to flow the same fields to those pages/tables - Referencing will not be easy.
Reporting aspect would be solved easily by Either Dimension or by Item Attribute.
Dimension (Shortcut) would be perfect fit for the same.
Regards
Karan