Thanks for your comments and your cheerings!
Rock-bola: I’ve just translated the walk through of this project in English, so you can see it from now on.
Truthhunter: I explain in my making of, among other things, my process for the texture, which is actually only painting thanks to the great function:Polypainting
.

Ashaiad: I could indeed have increased the effect of the SSS on the jaw area, but I also had to take into account the particularity of this model: it has a really rigid skin (scales) which should hardly let the light go through. besides, some areas of the model are done so as not to let the light go through (some areas of the Back Scatter Color texture are painted in black).
Bartp: I’ve used Mental Ray and a SSS shader for the final render.