crude contours after finishing pass

I have been trying to cut a 3D head using a Machine Relief toolpath in Carveco software. I carried out the roughing cut (1/4" ball end) and then the finishing cut (1/16" ball end). The end result was far from satisfactory as it still has very pronounced ridges/contours and lost much of the detail of the original model (not like the smooth examples I see in tutorials). It would seem to me that further sanding would just make it lose it's form altogether. So my questions are:

1 What is the standard procedure here? Is there a particular tool I can use to get such an intricate surface smooth?

2 As one needs to change router bits in this procedure - what is the standard way of making the z values match (as one may protrude from the collet more). I have a corner probe but it seems a bit erratic.

Than you,

Robert