Character Retopology

I’m slowly getting into character muscle sculpting, painting and retopology.
I’m wondering about Make Human. Supposedly they have good updates for retopology with characters.
If I was to make about 10 similar characters for a crowd system. Basically use the same mesh for all of them?
Reposition and remove stretching?
Does a characters retopology change that much from a few simple facial features being changed, arm size, etc…?

Not sure how the auto-retopo softwares will handle it in this area.
I’m sure a good understanding of how to do muscle body retopology for humans/creatures by hand first would be a big help.
Looking for some tutorials soon.(Any reference would be great…thx.)