For the second sort (as in the 3rd and 4th pics), select the part intended too become the spot and copy it into a new layer. Pump up the Brightness. With a large, soft brush, erase the sharp edges to blend in smoothly with the layers below. Or apply gaussian blur and set the layer blending to 'Screen'. Again experiment with multiple layers with different blending settings and brightness/contrast to get just that look. Lemme know if anything else comes up!