True, it is up to the user there though. Known-hosts may be a good thing, or may not. Config is empty of detail by default so that seems not an issue.
I have used only Workstation on most hosts, with a small foray into server on one of my Pi hosts and was dissatisfied with it (could not get wifi properly functioning) so reverted back to workstation there. I cannot say about other spins.
This will copy your private key(s) too. If you’re managing a bunch of remote systems, all you want on them is your public key in the “authorized_keys” file. You won’t have that on your local system, so you’ll still have to do ssh-copy-id anyways if you want to use key based authentication.
Maybe and maybe not. I have used my method on each of my several hosts and doing so enables bi-directional ssh between hosts since each has both the public and private keys. Using the ssh-copy-id command only enables ssh in one direction between those 2 hosts because the private key is not also in place on the second host. The public key is in authorized_keys and the private key is in id_rsa
I agree that if remote hosts have admins other than yourself the storage of the private key there is probably not a good thing. My situation is that all my hosts are only accessible by me so it is minimal risk for me.