How long since it was last used as a food serving Vehicle?
2009...….. current registration and runs good enough to pass California emissions.
Are there any outlets to run appliances such as a food processor?
There are not. But there is an inlet for a generator and or extension cord which goes to a fuse box which an electrician can easily wire outlets to
Do the refigerator run while the vehicle is in motion?
The motor has a compressor on it. It does turn with a switch on the dash but is inconsistent my mechanic told me more than likely needs freon. Refrigeration for vehicle needs to be serviced more than likely... when hooked up to an electrical outlet the compressor seems like it runs just fine and it does get cooler but not cold enough in my opinion.
Do all the kitchen appliances work currently; fryer, griddle, and reefers.
As far as I know everything lights up with propane. I suggest you have it inspected by somebody who knows what they're doing I am not that person
How big are the fresh/grey water tanks?
There is only 3 sink wells visible in the video. Is one just covered up. It listed 4total.
There are indeed only three sinks. certainly room on both sides of existing double sink to add I think on either side and lots of room underneath for plumbing.