Re: Auto genny on/off?
Some of the inverters or inverter/chargers above the basic models have an AC transfer switch built in - when they see AC from a shoreline or genny they stop inverting and transfer the load to the external source. I think we paid about $400 for some small inverters with no charger but automatic change-over, to use in UPS fashion with external batteries already present. Important: whatever does the power transfer must transfer the neutral as well as the hot lead(s).
Top-of the line inverters will even do the genny run request, though you may have to buy the companion remote control to set the start/stop points. A friend had a Xantrex in his RV, and I had downloaded and studied a remote control manual so I could provide "tech support." A "GS" (Generator Start) series Xantrex inverter with a RC/GS remote will let you run the genny from your armchair, and even has a programmable "Quiet Hours" feature so it will delay the auto-start if you are in a park that restricts noise.
I'm sure there are other brands out there that will do the same thing, if you hunt around.
Someone said "Making good decisions comes from experience, experience comes from bad decisions." I say there are three kinds of people: those who learn from their mistakes, those who learn from the mistakes of others, and those who never learn.