Hey @Willis71,
I will try to break it down pretty thoroughly.
To start, it is always recommended to try and wire your nodes together as this will ALWAYS provide a better connection than if they were connected wirelessly. Mesh allows for the nodes to be easily linked wirelessly, where it may not be possible or would be unreasonable to wire the nodes together. If you are using a wired backhaul between all of your nodes, there is no need for a wireless backhaul. In fact, in the event your ethernet cables disconnect, your nodes will automatically transition to using a wireless backhaul.
Connecting Your Decos:
Every Deco Network is made up of one "Main" node and multiple satellite nodes. The ports on the nodes does not matter as your Decos will automatically configure the ports for your needs depending on how you connect them. You can connect a Deco directly into the main node, or you can pass your Decos connection through a network switch to "relay" the backhaul to the main node - or you can daisy-chain and connect a satellite to another satellite if needed.
Ideally you will connect your MultiGig port to your ISP Modem or Gateway for the best speeds, but other than that the ports can be used flexibly. If you have extra multigig ports available, I would recommend using these for your backhaul as your backhaul could become a bottleneck in the event of large downloads/network traffic.
As long as your nodes and your devices can find a path to the main node you shouldn't have any problems.