Upgrading older system...

[FishBut]

Hi, in process of getting the system wired up and running a DSM 300, RD424D radome and the two E120Ws to the Raymarine SeaTalk Network Switch and had a couple of questions. The Raymarine install guide specifies "high speed" and "low speed" data connections on the Network Switch. It can't find where it specifies which devices should be connected to the high speed or low speed connections. From the 4 devices mentioned above, can you tell me which connections (high speed or low speed) should be used?

Second, both the SeaTalk network switch and the RD424D radome have a "ground" connection indicated. The radome has a green wire in the power cable and the network switch has a connection for power, neutral and ground. Should both of these "ground" connections be made to the boat's "green wire" bonding system? That is the best I can tell from the install guides but wanted to check. Is the purpose of this additional grounding related to lightning strikes or something similar?

Thank you!