You have a very good question. In my opinion, there will be a decrease in power consumption, BUT, it is going to be small. I'll answer your questions first, and then provide an explanation:
1. the pressure ratio will change. Instead of the pressure going from 14(intake)-19(post compressor)-17(post throttle)-14(back to intake), it will go 14 (intake)-12(post throttle-*guess*)-17(post compressor)-14 (back to intake).
2. when the throttle is on the intake side, the pressure will decrease post-throttle.
3. I am not sure... it would depend where the gas is removed from the system. Could you draw a very basic flow diagram and post it? It really depends on a few critical factors ...
4. Most programs are able to determine the suction pressure (given a pipe size, restrictor (throttle valve) opening, etc. The power consumption will decrease.... albeit -very very slightly .. my guess, close to the 2nd decimal point. The reason is that less pressure (less atoms being moved and allowed to have friction), whereas more atoms (higher pressure, more atoms to create friction) has more friction. If the system has an overall pressure differential which is lower after the modifications, then the pump efficiency should increase.
I have about 10 years experience on refrig plants. They rank as one of my many favorite plant types.
I hope that I explained this well. Feel free to comment on the parts which do not make sense ...