Clients connect to SeedDNS and connect to nodes but how do nodes connect to each other?

Im running a node and im also generating with it. I accumulated 200 Coins and I would like to send them to another wallet using CLI.
Im getting the message: Fee estimation failed. Fallbackfee is disabled. Wait a few blocks or enable -fallbackfee.

How do I enable it? Thx

Im running bitcoin on a Mac. How can I use a custom .conf file? On linux I cause parameters like -conf right?
I pasted the .conf file into Application Support/bitcoin but I need to let the app somehow know that I want to apply the .conf file to it.

Any advice?

Im fooling around with my own Bitcoin fork.

I generated my own genesis block and modified chainparams.cpp.
I inserted my own Merkle hash into genesis.hashMerkleRoot and compiled it.
After compilation its reverting to the standard Merkle hash and I don't understand why.

Anyone having an idea why?