I'm not at the boat, but here goes:

1) "Used the orange/green on the former; have now tried both pairs on the latter. Manual says yellow/blue is the "listener."....

See page 56 of the installation manual, video cable pinouts:
Pin 7 Orange = RX_B (RS232 GROUND)
Pin 8 Green = RX_A (RS232 POSITIVE)

2) "Baud set to 38,400. Which protocol: 232 or 422? What about the "receive waypoints" button? Anything elsewhere to set?"

Baud is correct for most AIS units (default). Use 232 for protocol. I have the "receive waypoints" checked.

I think the pins and protocol will solve your problems.

Menus get easier once you start to get familiar with the menus in touch, and the fact that you can "back out" of where you are just by touching somewhere else (vs. hitting "esc" several times).