"When I ColorSort an embroidery the number of color blocks produced varies."
The ColorSort process does not just put the same color blocks together. It checks for overlap between areas, therefore depending on the overlaps, the final number of color blocks may vary, even if you are Combining a similar number of elements.
"I ColorSorted my design. Why are there so many colors in the Color Select area for it?"
If you use ColorSort on a multiple selection or group, the number of colors seen in the Color Select area may be more than if the same embroideries were combined. This is because ColorSort looks at the embroideries within the selection or group separately. To keep embroidery elements editable in your project and minimize the number of colors when stitching out, use Export with ColorSort to create a version for stitching.
Use Design Player or Print Preview to see how many colors the exported embroidery will have, according to the current options.