i'd suggest running both oil feeds if your using an internal feed for vct, especially if your not revving it much. in standard form the vct has its own 1.5mm feed and the 25 head has 2 x 1.5mm feeds, so a single 1.5mm for all 3 wouldnt be ideal.
a standard 25 or 30 oil pump will be fine for a mild 4wd setup.
a small highflow turbo would probably be perfect for 4wding, even a standard turbo if your not after any more than 180rwkw.
use a 25det loom and an ecu to suit a 25det