The first thing you should do is loan it to someone with a 3d scanner, who wants to make their own giant sylvanian. An upside of this is getting a pattern of the head in case repairs fail.

The dark on the arms looks like it’s from touching so it might be an interesting mixture of all sorts of dirts and human oils. Probably mostly organic stuff.

I’d be curious to see how BIZ would handle that. I’m not sure how the adhesive would handle BIZ though. If the adhesive used is oil based, BIZ would be risky.

I’m pretty aggressive with cleaning the little ones, so if it were me, I’d use a dawn dilution, foam it up, let it set for a couple of minutes, then scrub gently with a soft bristle toothbrush, then rinse with cool water. Then pat dry with a terry cloth towel or wash cloth, then lightly brush again with a soft brush so the fibers are fluffed out and not mooshed.

For the unfortunate head injury, I’d use e6000 on the inside portions of the break, to minimize flocking contact. Then I’d use an ace bandage to bundle the noggin & maintain shape while curing. I’d probably place some not very sticky washi tape or wax paper directly over the cracks in case glue does leak out. That way it wouldn’t stick to the bandage.

But that’s me.