Can you please tell me which repair is more critical for a 2002 RL: (1) Power Steering Pump leak, (2) Rear main leak, (3) Cam plug leaks?

Hello, it's more about how bad the leaks are. All of these leaks would be costly to repair. The power steering pump leak - if large enough and under pressure - could pose a safety issue. Rear main seal and cam plug leaks if insignificant should be OK to "watch".

Power steering!