Britain, let's start at the tank, you will have a large line that gravity feeds the pump on the pressure side. The pressurized oil will flow through all the oil gallies or galleries in the case. The number of stages refers to the pressure side and the number of scavenge sides. So 1 pressure and 1 return (scavenge) is a 2 stage pump, 1 pressure and 2 returns is a 3 stage etc.
The scavenge sides suck oil from the engine. I would use a 3 stage on your engine. 1 scavenge on the sump, on the oil drain plate and 1 for the turbo drain.
You will have a return line as well, this returns oil to the tank. Typically you would want to have an oil filter and thermostat on the return line. Run the line from the thermostat out to your external oil cooler and then back into your oil tank.
You can use a 911 oil tank or an aftermarket type. You can run the oil lines up the rockers just like on a 911. You make even want to use 911 hard oil lines and thermostat on your project, it will fit the body easier.
Here is a picture and an link for multi stage dry sump set ups. Autocraft makes nice pumps for VW applications.
Ed
http://auto.howstuffworks.com/framed.htm?p...ce.com/info.htm