No idea how many layers the material is, but they are absolutely waterproof. Unless you put a hook through them or fall on your knees repeatedly like I have. A big of aqua seal has kept them dry though. Also comfy in warmer temps. They breathe extremely well.
I'm 5'6.5" or so and wear 30x30 jeans up to 32x32 which are usually too long. I got the "Short" version of these and they fit me absolutely perfect. Hope that Helps