First AutoCascade

I'm planning on making my first auto-cascade system this winter. It needs to hold 50W at -55C and will hopefully hit -80C under no load.
It needs to run worldwide so I have chosen to use the SC12CLX.2 compressor from Danfoss which can run on 50/60Hz from 220-240V.

1st stage refrigerant: r404a
2nd stage refrigerant: r23

I'm going to use the same evap as my single stage system which is a modified swiftech heat exchanger with holes for cartridge heaters used to maintain temperatures through a PID controller.

What size Plate exchanger will I need? approx?
How should I size the cap tubes? assume 6ft hose to evap.
What pressure of r23 will I need? approx
Do I need an oil seperator? Assuming POE oil.

My single stage has a static pressure of about 130psi r404 which gets me to -40C and can hold 200W at 0C. It uses 12ft of .040" cap tube.

Also, I need to bring the evap up to 150C occasionally, possibly for hours at a time. Do I need a solenoide to pump out the r23 for this?

I'm happy to supply pictures.