I am thinking you want to know about the colorization basically. The people were selected out and placed on BG.
You're right.
Desaturate.
New layer. Paint a color in, such as the skin. Change blend mode to color and adjust the opacity to your satisfaction.
Make a new layer for each area you color. That way, you can apply different opacities, etc. You can also erase if you bleed over another color area.
New layer: you can lighten, even tones, minimize features this way: create a new layer, fill with 50% grey. Change blend mode to overlay. Select dodge tool and lighten areas to give them flat, almost cartoonish effect. Use a soft brush, low exposure. I start with midtones, this is usually enough since I'm not looking for that exact effect. But you can finish detailing with the other range settings.
If you want to emphasize something like Barclay's tie, then don't change the blend mode or try a blend mode of vivid light, etc. Experiment.
Okay, there are certainly more steps and techniques other members can offer. This is the simple way I would do it.
Oh, IDK really how the shine was added to his suit. It may have been like that already. But I would duplicate the suit, use the plastic wrap filter and lower the opacity or use overlay or both. I'll have to try that. Again, speculation from someone who is really not a "guru," especially with colorization. But it sounds like it would be fun to try!Here's a quickish one without doing the hair. I did try the plastic wrap on the jacket and it's an interesting effect but not the same as his suit jacket. Anyway, I hope this was of some help.I can see there's more to work on here to create the outline you see on your examples.
you should be able to do it with "High Pass" filter.
duplicate the original layer apply the high pass filter to it about 70%.
then change the blend mode to "vivid light"
duplicate that layer a few times to make the effect stronger.