If you feel lost, with all the data, and decisions thrown at you, get somebody better at this than you to make visuals, of whats happening.
I do a drawing, showing a ball, with a flat spot, that is at sea level elev. This is the State Plane system. Grid to ground scale factor is 0 where it intersects the plane. Then, I make little mushrooms, where the plane is below the surface, and we have come UP to ground. And, inverted mushrooms, where grid is ABOVE ground. These little local systems, are great, if you don't move too far away from the origin or stem of the mushroom.
then, I make another plane, which is inclined at another angle, (different origins) to depict it. After an hour or two, looking at this, it all falls in place, for many folks.
Internally, the native system the LS runs with is Lat Lon, so that data can be EXPRESSED in many different forms, That is one of the finest features of the LS. (My totally unbiased opinion!)
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