just use complete half shafts, NA lsd usually 6 bolt, turbo 5 bolt, diff spline different, hub spline same (except gtr), 20e will struggle to spin 2 wheels so will prob no wheel instead of 1 wheel
i think i know the custom turbo you mean, it's a turbo off a cappucino with a chrome front cover?
you, and they guy that did the turbo have no idea of spec? who could guess, i reckon 70kw, as it comes on boost the wheels will hit the housings and fly off
could have a bit of an air lock in the heater core? could try filling cooling system from heater hose, hard to say about noises, if it's making a different note should check belt is timed properly etc
i drove a 33 with a turbosmart twin port mounted on the pipe down inside the bumper, it wasn't quiet!, pretty much everyone gave me the death stare, or some will know it as the mother in law stare, the straight pipe exhaust with screamer didn't help much either
25det rwd would be too long i'd be guessing (and electronic anyway), as 32 gtr is too short for 25det box as above pic shows, just a 32 gtr or gts4 drive should do it? (both are mechanical)