All you have to find out regarding the new vans electrics is the plug fitted to it. If it is not the same system as you have on the tug presently is to decide whether you wish to retain the current tugs socket and change the van or vice versa. Don't worry too much about how the new van is wired, the trailer connections should be wired to an Oz standard - see this link for the pin connections. Any auto electrician will wire the connectors to this standard. When you get your installer to wire up your brake controller (if you can not do it yourself0 he will wire it up correctly to the socket on the tug and things should work OK.

In the short term, if you have a different style connector on each vehicle you can purchase an adaptor to convert one system to the other (providing a 12 pin connector is not part of the deal.) If the new van has a 12 pin plug on it I would suggest you retain it and change the tugs socket. The large pins are rated at 35 A which are necessary to carry the 12 V power for the fridge. I suggest you have the hot wire for the fridge wired to pin 9 and that the installer use 8 gauge wire for the connection. Also have him wire in a relay connected to the ignition or accessory circuit to cut the fridge wire when the motor is not running (this prevents the fridge from flattening the starting battery if you leave the fridge connected when the motor is not running.)

When selecting a brake controller, go for a proportional action one as they give smoother braking.

Baz - Is this the thread you were talking about.