On a 24 X 24 X 24 footing how much rebar do I need to support? A 6x6 column?

Answer 1

Assuming the numbers are inches, You don't need any reinforcement. However if you feel you must have reinforcement use three re-bars in each direction, laid horizontally, forming 6" squares. or you could have fiberglass reinforcement added at the batch plant

Answer 2

You really don't need any. If it will make you sleep better at night, I suggest 3 pieces. 1 piece every 6 inches or so.
But 2 feet of concrete is going to be pretty solid.

Answer 3

too many unknows to answer