Okey dokey. Here is what I found from your files.
1. COWBOY HAT. This one worked fine for me straightaway, so I'm not sure what the problem was. The only thing I modified was the surface texture alpha channel to bring reflectivity down to 4%.
2. MONK SUIT. This also worked mostly fine. I just had to modify a few textures. I changed the mask texture so that the mask was only in the red channel, as opposed to all 3 RGB channels to keep in line with the other mask textures. And again I modified the surface texture alpha channel to 4% reflectivity. The only other thing I noticed was some minor skinning errors around the neck - it's important to keep skin weights the same as in the templates. Any deviation from that will cause gaps.
3. FEMALE HAIR. I wasn't able to replicate the texture error you showed in your screenshot. Again I modified the surface texture alpha. Now this hair model isn't all that great to begin with, but it works. The transparency issue is a little more tricky. Even though the texture does not contain transparency, each individual piece of the hair gets sorted in a back-to-front order, that is why some parts of the hair seem to be showing through other pieces. Now I'm not sure how Blender handles things like this, you could probably Google it, but you need to set the drawing order of the hair pieces so that the innermost pieces get drawn first, and outermost pieces get drawn/rendered last. I actually released a free tool for 3ds Max users last year on Scriptspot that helps with this called "Draw Order Toolkit" :
https://www.scriptspot.com/3ds-max/scripts/draw-order-toolkit
I've attached the modified files.