Yes! The main thing is to try and minimize the length of the I2C cable, because a longer cable will increase the overall capacitance of the I2C bus, and too much capacitance will cause communication errors. Ideally you'd have a short cable to your motor driver and then a long cable (if necessary) to the motor. Bus loading is also a potential issue, as this is the same I2C bus used by the power system, but in theory it should work.
And for the firmware, the Hardware.h and Filenames.h files define constants for the hardware functionality. Those constant names can then be searched on to see how they’re used in the firmware.