By fog you mean murky water(when you enter them you see worser then you are out of them) for I thought that if I want to do so I need an Env_Fade? :
I knew most of the stuff you told me here like the animations, random tiling, invisable textures,water and scroll textures, I didn't know that the skip texture had no other function!
You forgot light emmiting textures ~ and that they will only emmit light when they can be toggled +0 +A.