I have some experience with this 
YES! You should calibrate the flow rate and flow dynamics for a 0.2 nozzle; it will be slightly different than that of a 0.4 nozzle.
If you are on an X1 Carbon, don’t use the auto flow dynamics calibration on the printer. The engineers have limited the maximum (can’t remember the exact number right now EDIT: found it: 0.060 max via auto calibration). The auto flow rate calibration on the X1 Carbon is spot on (I’ve verified via printing an open single walled cube and measuring the wall thickness and done the math).
For determining the flow dynamics/pressure advance: I found the manual “line” method to be more accurate, if you use a magnifying glass to look at each end. I’ve tried the “pattern” method, but for my eyes it was as discernable as the “line” method. But each their own.
P.S. Don’t be afraid of getting into the 0.1 - 0.2 K values for the flow dynamic values on a 0.2 nozzle. I’ve had several filaments that was where the cleanest lines were.
EDIT: corrected K values in P.S., one decimal place off.