The result of the whole sculpting process was a multiple subtool model. At this stage the overall topology and polycount was very high and became difficult to handle, especially the head subtool, which was still a DynaMesh. So I used the Qremesher option for the head subtool, which changed the topology and reduced the polycount. It didn't matter that the polycount was low, because the head subtool would be subdivided normally to bring back all the fine details using the Project All option.
Now there was a cleaner and more even surface to keep working on, and from here I kept sculpting and painting the model (Fig.08 - 09).
Fig.10 shows the poly paint of the whole model after the Qremesh and projection. The Project All transfered the poly paint as well as the sculpted details.