Hi Eli,
I have not tried it in system but these 2 enhancements should be possible. Please find my answers below.
1) You can activate the operators for any specific Attribute of a component. SPRO-> CRM -> CRM Cross-App Components -> Genil / Object Layer -> Comp-Specific Settings -> Define operators for dynamic queries.
2) If you meant, adding search values dynamically for the Main category field, you can do it in GET_DQUERY_DEFINITIONS method of your view IMPL class.
Regards,
Nitish.