This is my subject. Removing is more an issue than driving.
I have driven 1/2 and 3/8 with an electric demolition hammer. Use a unit drawing 10-15 Amps with a ground rod driver bit that cups over rebar up to 3/4. That current draw translates to driving power in ft-lb or Newton-m. They drive in a few seconds literally at that energy.
The depth depends on the pull out strength required. For me, a foot to 18 inches was more than sufficient, how you attach things above to not pull off the protruding stake is of greater concern than the rebar pulling out of the ground. There is a great burner blacksmith who makes forged u-shaped stakes, easier to drive and pull for small structures.
If you are putting up a greater than 20' dome, something with a big wind load, a tower or big art project you need professional help AND the advice of teams that have put up similar.
Getting the rebar out of the playa is a different story. The vice grip twisting advice is bullshit. Digging around, adding water and using a big ass lever, like more than 10 feet, is the only way. I spent an average of 15 minutes per 12-18 inch buried rebar getting them out with an 8 foot lever. 20 rebar stakes, 5 hours.
If you cannot seriously get the rebar out, contact DPW. Very seriously. They will be cranky. The effects of a piece of upright metal left buried in the playa is a severe safety hazard and liability hazard to year round playa visitors, including high speed racers.
So just saying, the pleasure of insertion is weighed by the lifetime of responsibility dealing, as it should!