1) we could make the distinction of atmospheric pressure there, but that's semantics. Once we establish gravity, and we measure the atmospheric pressure gradient (which I hope you'll agree on), it is evident that at the altitude where you'd probably put a container, there is a hard vacuum.
Simple observations like sending up a balloon and seeing the blue (air/atmosphere) fade to this blackness which is commonly called space is good empirical evidence of the pressure gradient fading from 14.7psi at sea level to almost nothing, even better than what we call an ultra-high vacuum.
Indeed the pressure gradient is a curious question, regardless of the model. If there's no vacuum of space, and a container, it's explainable by the denser molecules moving down toward the earth and then less dense ones moving upward. We find the same conditions in the ocean, where the pressure increases as you go lower. There was even one under-ocean "lake" discovered that consisted of an extremely dense pool of salt water. Pressure decreases as you move higher. Then above the oceans you have the far less dense atmosphere. Question then is what's above the atmosphere. Traditional science holds there's a vacuum.
"Gravity" would have to hold everything down and resist the force of an infinite vacuum, which I simply can't comprehend. I've seen vacuum experiments where you had a bowl of water on the bottom with air around it, and then a vacuum at the top. When the vacuum was "turned on", not only did the air evaculate the chamber, but the water evaporated, turned into gas, and then also evacuated the chamber ... gravity notwithstanding. So in a sense there was a pressure gradient already. It be interesting if within a chamber, on a small scale, we could recreate a simulation of the pressure gradient we have in our atmosphere and then give it a shot. I'm very skeptical that gravity can overcome an infinite vaccuum.