One point calibration appears to increase the accuracy to +-0.1 hPa. Can this calibration be completed in our production facility right after soldering?
Yes. With a reference pressure sensor.
Will the OPC calibration permanently set the RPDS_L/H registers and allow for the increased accuracy over time? Or do they need to be reset periodically?
The value needs to be stored in your system memory. Then, load it to the sensor PRDS_L/H registers every time after powering up the sensor.
Also, can the temperature accuracy be OPC calibrated at a single operating point to increase the accuracy of the temperature reading near that point? Would this be using the TEMP_OUT_H/L registers?
The TEMP_OUT_H/L registers give relative temperature output. It also can be calibrated with a reference temperature sensor. There is already temperature compensation built into the sensor HW. After OPC, the range is +-0.1hPa (in spec).