You seem to have it figured out pretty well. Notice that under the "VOLVO" on the blck plate on the compressor housing it says "TD05-12B" and "Made in Japan". That and the metal ring are the clues; it's a Mitsubishi.

Also the compressor bypass valve built into the housing rather than connected to the output hose is a dead giveaway.

I've never seen a "Dawes Device", as I mentioned, I have "Gus's Device", but from the pictures on the web page, I think you've got it; the wastegate actuator is indeed under the compressor.

As wbain said, adjust the controller so you can blow through it(from the hose nipple towards the Dawes hose) at first, then adjust it to your liking. If you do get it backwards, at the first aplication of throttle, the boost will go through the roof and the overpressure switch will shut off the fuel, kinda like a bucking bronco.

To reiterate wbain's concern: If you're going to use 12 PSI very much, your cooling system had better be top notch or diaster will surely follow.