Raymarine C120, Autohelm 7000

[Don1500]

I have a few questions about my new (to me) boat autopilot system.
It has:

C120 display at the fly bridge
Autohelm 7000 control panel at the pilot house (main helm)
a hydraulic steering system
ALL this works according to the seller.

1: It has a seatalk interface but I believe it is not Seatalk(ng), are the connectors different? can I get a converter?
2: I would like to put an A7 series MFD in the main helm station so I will have wifi throughout the boat, is it possible to connect it to the C120 via seatalk, and if so can I enter route/waypoint info through the A7 MFD? (The C120 uses a different type of memory card and I will have to get more equipment to program them on my PC.) I would like the A7 to be the master controller for the system.