...and for context, the Heavy Crawler is the large grid rover on my workshop

It's equipped with atmo, ion, and hydrogen thrust, so it's capable of operating most anywhere. I did test it's payload capacity in 1.0 gravity using the Heavy Crawler, and it was able to stay afloat, though with difficulty. I haven't written down the acceleration numbers, but it wasn't designed to be particularly nimble and quick.

can it withstand gravity and what is the speed on it?

The vehicle in the 2nd photo, the one being carried by the dropship, is the combat crawler. It's a small grid combat vehicle.

what is that vehicle in the second shot?