Welcome! Folks here are good help for questions like that. First have to ask, did you buy this coach from a dealer, and did they give you instructions on everything?
As to your water heater, try checking the valves. You probably have plenty of hot water, but one or more of the valves are closed.
Someone with an Outlaw will hopefully help out here, but the compartment lights on a trailer I once had were controlled by a switch near the trailer door. Some, like my current Vegas, only have switches on each light.
RV manuals are ridiculously inadequate, unlike your exhaustive car manuals. That said, you should take the time to go through the RV manual, and the component manuals that should have come with your RV.
There's a learning curve when you buy any RV, we've all been there!
May the trails always twist in your favor
May the tales always end in good light
May you have more friends than one campfire can hold