Check out these awesome new updates:
NSS, NSO Series Software update 18.3
http://downloads.simrad-yachting.com/software/index.html?r=1007
http://downloads.simrad-yachting.com/software/index.html?r=1552
Simrad GO Series 18.3 Software Upgrade
http://downloads.simrad-yachting.com/
The same cables can be used. The Es needs to have the lighthouse 3 software update installed. The update is free and can be downloaded at the following link:
http://www.raymarine.com/view/?id=15032390044
The Quantum 2 Doppler is compatible with all eS and gS series so you can upgrade without changing out the eS9.
Please let me know if I can help you with anything else.
You can connect STng to NMEA 2000 with an adapter cable. (see link below)
https://www.boemarine.com/raymarine-seatalkng-to-devicenet-male-adapter-cable-1m.html
You can go to Simyamaha.com for the info to integrate the SC500 to the Garmin 942xs.
Please let me know if you have any more questions.