[CA] [CA11] Interface Garmin 742xs to Ray ST8001 Autopilot

[YoBub]

My thoughts on this configuration have evolved a bit over the winter.

I currently have the following:
E120
92654-S radar array
DSM300 (with unknown transducer - probably B256)
ST8001 Auto Pilot

Newly Acquired, not installed
SR100 Sirius Weather
SeaTalk HS ethernet hub
Garmin 742xs Chartplotter
Standard Horizon GX2200 VHF

Right now the DSM300 is connected directly to the E120 via ethernet. Radar direct to the E120.

The Autopilot is connected to the E120 using a flat seatalk cable (4 wire flat jack), and another seatalk cable out to an unknown location. The autopilot also has a pair of NMEA0183 wires connected, which connect to a junction block with a whole bunch of other wires, so it has seatalk in, seatalk out, and NMEA0183 (I think). Not sure what it all does or where the other seatalk cable goes. I looked but couldn't find any other devices.

Here are my questions:

1) My new Garmin chartplotter has an Ethernet connection. Can I connect it to the SeaTalk HS hub, and share some type of data from the E120, such as depth, water temp, maybe others? I don't expect to share radar or fishfinder info.

2) I have read that the E120 can do some types of protocol translations between NMEA0183 and other protocols. If I can connect the Garmin as outlined in question 1, can I decide whether to use the Garmin or the E120 to drive the autopilot? (turn the function off on one or the other via software)

3) The VHF has a built-in GPS, so it doesn't need a GPS signal from the chartplotters. It has an AIS receiver that I would like to feed out to one of the chartplotters, ideally to both. It only has NMEA0183 output. I've read that I can only have one "talker" on an 0183 network, so can I send that AIS signal through 0183 to the E120? Not sure if that will screw up the auto pilot.

I've been searching and reading all I can about this networking, but still don't have it quite figured out. I feel like I'm getting closer but don't want to screw anything up.

Any assistance would be greatly appreciated!