(VelocityRacing @ Jan. 14 2007,13:54) Leave the plug in if you are running the oil cooler. Take it out if you are running block off's. It has no effect on the oil going to the turbo. It actually causes the oil to go thru the oil cooler. Without it, the oil cooler will not cool the oil.
You can run full oil pressure, but you should run a #4 steel braded line, as it will serve as flow control. Too big of an oil supply line will drop your oil pressure in the motor, and will be hard to return back to the oil pan.