1/2" NPT will be a good size to go with. A line 1/2" ID or larger would be good as well.
You shouldn't have any excessive oil pressure issues on a stock 3VZ motor... A -4AN oil feed to the turbo should work without any problems. And for the usual oil drain FAQ's, make sure there is no kink in the oil return line, try to keep the return sloping at a downward angle and avoid using tight angle 90deg fittings.
I tapped the coolant from the throttlebody coolant line... It runs through the throttlebody/IACV and then to the turbo and back into lower intake manifold