Pretty well all this can be done in other good paint/edit programs -- I've done the same in PaintShop Pro.

Look into saving the mask seperately from the image. Sometimes you might need to work on the same area in different image files, such as a transparency map, a texture map, and a bump/displacement map.

And this image was created in Poser 5, using the same texturemap and lighting, and some shader nodes to warp the gamma curve. You could change the colour of the face by adjusting the base diffuse colour as well.