This should resolve all questions.
www.microchip.com/stellent/idcplg
Explains in detail how the BLDC motor works. Note it says DC, not AC. It is 3 phase, but DC powered. The voltage flips from + to - in relation to ground. The only part that has me a bit puzzled, 3 Phase requires 4 wires, whether it is AC or DC, the 3 phases + Neutral for AC, or ground for DC. The ESC has only 3 wires, so where is the ground?
And yes you can push/pull with DC, pull with Positive and push with Negative. In relation to ground or zero (0). Thats how PC's work, Check out the power supplies in a computer, you have +5 v and - 5 v in relation to ground.
The PDF has all the details on the motor and controller.