The lungs don't work until they inflate with oxygen. Vocal cords don't work unless oxygen is present. So no, no crying before birth. Not possible.
They've been seen to frown and make crying type faces in 3D/4D sonography. It's not really known if they can actually cry.
I dont think they are able too though I asume they are too comftable to bother trying.
No. No air in there. They hiccup, swallow, yawn, sleep, such their thumb and toes. But not crying.
I've not heard of that, but I know they practice swallowing and sucking and they can yawn too. Crying is really a main method of communication after birth, but before then they get everything they need from the umbilical cord, so I don't imagine they have anything to cry about while they're in the womb.