First of all, check that it does have gas stoves. Not all Westfalia's do, most of the early ones have alcohol (meths) stoves. The alcohol stoves are fine, so nothing to worry about. If it is gas then I guess it's a case of buying the right bottle of gas and connecting it to the regulator. The location of the gas bottle will be dependent upon the age, earlier vans (90-96ish?) are under the cooker, later vans it's in the back, possibly in the rear wardrobe. One of the other's can help out there, mine doesn't have gas.
The night heater, if fitted (it wasn't standard, at least on earlier vans) will be controlled by either a dial and switch above the sink if it is an early van, or via the control panel in the roof at the front on later vans. It uses fuel from the vehicles fuel tank, so either petrol or diesel depending on the van. The battery will need to be charged to get it running.
I'm not sure about the hookup. I'd agree with not plugging it in until you know more.
However, again it looks like it depends upon the age of the van.
Westfaliat4.info lists the charger that was fitted until '98 as being 250v, so I guess a different charger was fitted for US and Japanese vans.
http://www.westfaliat4.info/VW_Westfali ... UnitWM.pdf
For later vans, the charger is listed as supporting 250v/110v, my German is not good enough to work out if it is auto sensing or needs to be switched:
http://www.westfaliat4.info/VW_Westfali ... UnitWM.pdf
Maybe Liz (or Mr Liz!) or Sidepod can chip in, they know a lot about the chargers.
So it looks like depends on what charger you have. I think it's a case of getting someone who knows what they are doing to take a look. The charger is located under the fridge.
The charger and the sockets behind the driver seats are the only things that run directly off the hookup, everything else is 12v and runs off the battery or batteries.
That's probably added to the confusion rather than helped
dan