Heated O2 sensor power source?
 

Where's the best place to tap the 12v power for a heated o2 sensor?

That really depends where that wiring bundle is running from the 02 sensor. Are you going to use it for the factory 02 sensor? In that case just look at the wiring diagram and find a 12v wire into the ecu and splice it.

When I installed my haltuner I used a 12v off of the ignition.

James