Can a Full Node talk directly to multiple Harvesters?

[nomadengineer]

I have gone through the network architecture and the multi-machine harvesting.

However I still have some questions.
If we run a main full node, do we need to run an additional farmer to talk to multiple harvesters?

I want to switch over form windows to ubuntu.
Can I start a new node with the same 24 word key and just leave it to sync before moving my plots over?
Would this cause any issues because have upnp=True on both machines?

Is copying over the ssl/ca folder enough for the new ubuntu machine or do I have to use the 24 word key to have the full node properly provisioned on it?

Thank you.