A couple of questions

I believe the port is not for connecting to an external propane tank, but is instead a port for connecting a grill. It is low pressure so you would need one meant for low-pressure propane. These don't have (or need) a regulator since the pressure has already been reduced by the RPod's regulator. Our 2016 RP179 does not have that. It would be handy and I have thought about trying to add one. I just have not figured out how yet.

As for the battery, yes. The converter in the RPod charges your battery if low and maintain it at a float charge if it is fully charged. I added a 30A outlet to our house to be able to keep the RPod plugged in and also to be able to run the AC while we are home. Most of the time, I keep it at 80F because I don't want the interior to get too hot and I don't want the NC summertime humidity. In the winter, I can keep a small ceramic block heater going to keep the interior above freezing. That does not take the place of winterizing, but it keeps my LiFePO4 battery above freezing since it is inside.