[Elecraft] K3S K-line cabling

[David Aslin G3WGN]

I have upgraded my K3 with the KIO3B interface, so my PC is now connected via the USB port on the radio.
My question relates to the cabling for the complete K-line: K3S KPA500 KAT500 and P3
The cabling diagrams, even in the latest KAT500 manual, show the PC connected via the PC jack on the KAT500.  As noted, my K3 with KIO3B is connected to a PC via the USB port on the radio.  Which connection should I be using?  What difference does it make?

I also need to get band data to my Ultrabeam antenna controller (like a Steppir).  Where should I sniff the band data and will a simple Y cable do that?
73, David G3WGN  M6O