I'm a bit clueless about cnc but was pondering - can cnc mills typically find the edge of a work piece automatically or does the operator need to setup the workpiece manually?

In a production run is the 1st piece typically setup manually and the vice has some sort of locating stop so the cnc can reuse the position data for the 1st work piece?

Also when the cnc has a tool changer - is it assumed that the tool ends up in the same location as before or does the cnc somehow need to figure out it's new Z position - because the depth of seating can vary?