Well showing only images every x seconds is at least something reducing cpu load and having no problems at all. I guess even every 5 seconds would not be that much of a problem.
2) emergency stop activate ok. Reboot server is in printer and not a default function. Only if you have extcommands with it configured. So I'd leave these only in the printer.
5) If you unplug network the servers are not reachable, so we have no informations at all. Not reachable servers are not displayed. If you go to server list you will only see them as not reachable. Not seeing the printers of them is thus ok and wanted. We do not remember printers in monitor - we query them on connect to server so that is also th eonly way it would work.