@dbemowsk Your mancave project sounds EXACTLY like my setup. Two thermostats at quite a distance, fan (powerbar actually) gets powered when temps are <> a few degrees.
I'm not sure about the other questions. not sure what a node or controller is. I don't care how it works, really.
This was a mockup I had made back when I thought that arduino was the right way to go, but it seems there are all in one solutions (like the sonoff, except it lacks the extra sensor port) that will do it better.
I'm pretty open book about this project. I'm ready to buy whatever someone tells me to buy, as long as it's going to work, and will be somewhat reliable so I can stick it in the attic and forget about it.