Right now if we had a piece, lets say from an aircraft, it auto snaps in place. But if we wanted it to fill in the typically height of the grid square or Hexagon and the width and length, we have to resize manually. It would be neat to have either a shortcut key that can do that automatically. If that is there, I apologize. I don't seem to see or understand it.

I'm not sure what your request is, could you explain it in more detail?

For example, if you have a 3D part that doesn't fit the size of the grid, you can press something like E and it will resize the 3D part to fit the whole grid cell.