Where to find instructions - Remote Management for Linux and MacOS , sorry for the delay. I noticed that you work with Alexander and he has covered it via email.
Let me cover it here in case somebody else has the same questions in the future.
1. The port 22 is used when you connect to your server from the outside and the firewall permits it.
This feature is disabled by default, but if you like you can enable it:
Since the web console has the connection to the machine we can make this machine to open another port and encapsulate it to the already established connection (via which you can manage the computer from the web). And for that, we open a random port (like 11895) that you can connect to. This will work even if your firewall prevents connections to port 22.
2. Use what you think fits more,
3. For authentication, you can use login and password or login and pem file (for linux).
Thanks