within OpenBRF to see the errors you've. Taking a look at other materials that use the same shader helps a lot too.
Sometimes the loading order is just bad or a missing texture slot hurts the shading.
What do you mean, mate? Just use the diffuse as reference and mask out the shiny parts. The whiter the shinier.
Play with the brightness and contrast and paint over with a brush or fill selections. Stuff like that.
Oh, and always save as DXT1, the exception is to use DXT5 when you really need an alpha channel/ transparency in your texture.
You know, torn banners and so on. DXT5 compression doubles the size in memory and disk without any tradeoff.