Why is the compressor being replaced? If it broke apart internally the system needs flushed.

The dryer is usually changed for good measure.

Use only compressor oil on the o rings.

Oil will need to be added to the system, there are standards for component changes in service manuals. Some compressors come pre filled or at least partial filled.

I don't have a torque spec but spark plug torque is about right, lug not torque isn't