Of course, only when the SP is shown on the dial. But I wish he had this on his entire dial, or at least also on the first click, he should have it on the first click. Aside from the LE Judge Starro slave figure and Parallax (which needs a remake), Hal Jordan has always had lead Willpower in heroclix, as he should! Him and Batman are the epitome of Willpower in the DC Universe!

Not exactly. You would first get healed by the vine and if you still have Green Willpower shoving you would heal one more from the push. If the healing from the vine would take you to a click without Green Willpower you would take a click of pushing damage, because pushing damage happens after the action (healing from the vine in this case) has been resolved.