You need to fill your water tank when it's not way below freezing and then drain the hose and put it away using your 12V pump. Dump both of your tanks when it's not freezing and support the sewer line so it drains the waste out... no reason to store it if it does not hold water. When it's below 25 you need to run the Dynasty's heater so it warms your tanks. The rest of the time I'd use electric space heaters so you do not use up your propane and have to take the rig to get more propane. If you have AquaHot then less of a problem as 100 gallons of diesel will go a long time... the last 20 gallons you cannot use.
2. Guess anything is possible, but wifi camera systems are fairly cheap assuming the house has wifi to send the picture to you although I doubt security is an issue plus aren't there people living in the house?
3. Agree under the steps and ATF fluid.