Quickest way is to look for a thin (1/16 to 1/8") tubing going from the TXV on the high side, close to the evaporator coil, to a bulb (2"x 3/3") attached to the suction side. If it's a fixed orifice, you'll only see the high side enter the evaporator coil without anything strange in the way.
Time is money. The more you measure the more time it takes. Yes, both superheat and sub-cooling would be best. But if the manual for the condenser only has superheat values then that's what you go by. Always get the manufacturer's specs to use as a guide for your measurements.