No, it isn't. It's the angle of the cone, the metal used, the ratio of the thickness of the liner to the cone diameter, and the amount of explosive that makes an EFP different to other forms of hollow charge. There are a few ways to achieve all this, so an air gap might be one way to do it, but it isn't the primary difference.
The tank seats higher up than the crawling infantry, so yes, the crew are in a more vulnerable position.
In terms of relative height they are attacking while standing on a milk crate. The infantry attack on their bellies, or lower, so they are relatively immune to gunfire from the trench. One day you may come to the realization that all tank design has been trying to figure out how to get the crew closer to the ground without compromising their ability to bring a field gun to bear on the enemy.
The T-14 is designed like every other tank before it: the protected frontal arc receives the highest amount of defense against attack, with a greater emphasis on the side and top attack, and possibly bottom as well.
It will require better understanding of future combat to determine if Afghanistan/Iraq were realistic threat environments or absolute flukes. It is genuinely unclear to what degree side, bottom, and rear protection matter. We know that top protection is now a priority given the primacy of cassette ammunition and top attack weapons like Javelin. Whether that matters if you're dealing with OF munitions or not is an open question.
