Cluster requires root login between machines?

Hello.

Does regular cluster communication require root logon between machines? I usually set 'PermitRootLogon' to 'no' in my sshd_config for safety. I set it to yes to add a cluster node, but can I turn it back off now?

If it must be on, does it use keys for authentication? I usually also set 'PasswordAuthentication' to 'no' as well to prevent cracking attempts since I use keys to log in to my servers. I had to set it to 'yes' to join the node but can I set it back to 'no' now?

Thanks for any help anyone can provide.