Even if there is zero point energy, a vast untapped reserve of it, that doesn't mean it is free energy. Free energy means creating new energy. If we're pulling energy from the tenth dimension, then it might be CONVENIENT energy, but it's not FREE energy.
That is true, although I believe the theory of zero point energy would indicate that it is infinite (inexaustable), although I could be wrong.
However, the general concept of "free energy" is basically what you called "convenient" energy in the first place; even though it may not be infinite, it is free. Both wind and solar power is "free energy" in this respect: It's free, and it's energy. The main drawbacks of wind and solar power is their energy-to-weight ration and the dependancy on environmental conditions.