If a node is off, the server(s) hosted on it need to be somehow shown as being unavailable

How we handle this can be something we talk about. One option would be making the server's power button prompt the user if they want to power up the host node as well (create a job for each subnode to boot) and a job to boot the server. Another would be greying out / disabling the power button with some indication that the host node needs to be booted.