Not bad, seems as though you're on top of working with bools. Although just be attentive to the hardness of your edges for hassle free bakes, assuming this will be sent through a realtime workflow.
lighting channels only work with stationary/moveable lights so they don't work with anything baked, just the realtime lighting component effects channel characters/objects.
Yeah I think I saw the unreal demo for it. It works great for things like painting realtime clouds and even some air simulations but it's not ideal for this case.
I would look into the lighting and material definition / shading a bit more. As this is the weak spot right now with the realtime head. The highpoly looks really great btw.
Realtime hair wip, finished the scalp,base and breakup layers, will tweak it a bit more and i'll call this project finished. https://www.youtube.com/watch?v=DuScynsJoFU
Rendering in Mr or anything defeats the purpose of a realtime viewpoint shader. If your making game art preview in a real time shader in viewport, or use a game engine.
Found the link, it's SSAO Pro https://www.assetstore.unity3d.com/en/#!/content/22369 With it, I've produced very nice high-quality realtime AO in Unity. Very configurable.
So long as the topology of the scarf is similar to the body, and bone weights are set properly, it should animate fine. It's very common to do clothes this way in realtime games.
Ace beat me to it. Hourences explains it pretty nicely. Doesn't cover realtime reflections though, if you ever have questions about that then I'll gladly explain.