Hello and welcome to PSG.
Here's what I would do.......
First I would address the 'painting layer'. This layer needs to be where you like it before you move on. You have the right idea in how you can do this, but I would only work with the multiply, overlay, or soft light blending modes. Otherwise you could use any of the other color adjusting-adjustment layers instead of the 'painting layer'.
Once you have the overall coloration to your satisfaction, I would copy and paste a new 'face layer' and position it over the original skins layer. You can then use the Smudge Tool or the Liquify Filter to manip your face where you want it.
Then add a new layer above the 'face layer' and name it 'blending layer'. This way you work non-destructively.
This will be the layer where you will use the Brush Tool and/or the Clone Stamp Tool to begin blending your face with the original skins layer.
Tone down the tools!
Set your Brush Tools opacity and flows down so that your only applying a thin amount of color at a time. If you mess up, undo or erase.
Another method would be to add an adjustment layer to the 'face layer' in order to adjust your skin tone to better match that of the (adjusted) original skins color. You can always use the adjustment layer-layers mask to limit where the effect is being applied.
