Yes 9 and 7s have the same housings and exhaust wheel, it's only the compressor wheel that's slightly different.
yes the -9 will flow more power per psi compared to the standard turbos
A good shop that knows what they are doing can do turbos with the engine in the car in 8hrs and a clutch in 2hrs
dont bother changing the oil pump if you're not changing the crank and as good as the front diff makes the car it's not worth the expense unless you plan of taking it to the track a lot