You will need to get a 12 pin put on your car. depending on if you have a batter in the van, and assuming you have a fridge, 2 of the pins will need to be set up to go to the fridge direct from the battery and another should go from battery to aux for the battery. You would normally want to put on some kind of solenoid or device so that the fridge doesnt run your car battery down when ignition is off.
Brake control is not too hard. The auto elec will fit it in the cabin and run the wires as required. They are pretty routine for an auto elec. If it is all too confusing, I'm guessing your dealer will have a local guy who can do it while you go over the van. Might just cost a little more that way.