These are BMP files renamed to MIP. The game can't load BMP files.
Also, your face textures are 64x65. They should be 64x64. If you want higher res textures, you can also use 128, 256, 512, etc for the height and/or width. Just as long as they're powers of two.
Save your textures as TGA instead of BMP. I recommend using paint.net, as said earlier. While saving as TGA, make sure compression is off, as shown here.
I cropped your face textures to 64x64 and resaved everything as TGA (except the pants, which were already just a MIP from elsewhere in the game). I also hex edited the hat model to use COL_WHITE instead of COL_BLUE. This is what it looks like: