Yeah, the only thing I see is the hook up you mention so I'm think that's your fresh water connection.
The hose appears to be something a prior owner added. is that insulating foam that it's coming out of? I'd trace it to see if you can figure out where it leads. It looks like it's a male hose end exposed so that would make me think it's a "source" but...
I'd connect a hose to the built in connection while you're still at home. Turn off your water pump and see if you've got water pressure inside the coach. You'll also need to locate your fresh water tank fill valve in order to be able to take fresh water aboard.