Standard hydraulic hoses are not the same as ones rated for propane use. Your hydraulic shop might carry propane hoses but you should call and ask. Look for a shop that sells propane equipment and they should be able to get the hose you need.
With dual tanks I just let one run out and manually switch to the other. You can open both valves and run them together, but if you run them both out in the middle of a really cold night, you'll have no heat. You can also buy a regulator that automatically changes over for you.
No gauges. I know a tank is empty when the heat stops working!
2013 Jayco Jayfeather X20 E, 2008 GMC Sierra 1500 Crew Cab Z71 SLE