Upgrading MFD

[rvaupel23]

I'm looking to accomplish most of the same tasks here... Upgrading a SeaRay Navigator and E120 system to an eS127 and eS128 setup. My new HD Color Radome will terminate directly into one of the eS MFDs. I'll use a SeaTalk 3-way junction to connect my existing Ray240 and my existing SmartPilot to an NG backbone with the converter kit. Questions are:

if I use the E66066 adapter for the existing DSM300 transducer for a direct connection to a new eS MFD...

(1) does it matter which MFD (the 127 or the 128) it connects to?

(2) regarding all of these MFD connections (radome, NG backbone, external GPS antenna, IP camera, transducer, etc do they all need to connect to one "master" MFD where the 2nd is a "slave" or some connections run to each for all of the system data to be shared back and forth?