Nice analysis! I always liked a reddit post I saw once claiming that if Earth was actually flat, gravity would make it feel like a bowl (pulling towards the center) and flat-earthers would be talking about the Bowl Earth Hypothesis.
Having mountains that stretched to the vacuum would awesome for space exploration. Not having to deal with the atmosphere would allow for much more efficient engines to be immediately upon launch and no drag force to slow anything down or force the vehicle to be aerodynamic.
RE: What Would A Cube Earth Be Like? (Part 1)