Thank you!
At the kinds of speeds involved here, the mechanical strengths of the projectile and target are, relatively speaking, very minor factors. The behaviors of the two entities involved in such a collision can be more readily understood by thinking of them as fluids. This is why, for example, a remarkably blunt explosively-formed penetrator can get through thick tank armor.
If you want a slice of it, that hundred dollars a gram is actually orders of magnitude cheaper than what the earliest lunar meteorites sold for. (I have specimens of the moon and Mars that if I sneezed while handling them, I’d never see them again.)
That’s what I was going to say- although the same side of the Moon always faces the Earth due to tidal locking, it’s not always light or dark.
And yes, astronauts and space probes have beheld the far side of the moon (again, not always light or dark, but always facing away).
Yes, it’s mostly symmetric, but not quite completely. I’ve seen proposals that it’s the slight asymmetry in tidal effects that causes the mares, but I’m not sure if that can really account for it.