Its basically the same as in other games.
I never did enviro maps for FS, but iirc, in photoshop, if you create an extra channel (besides R, G and B ones), it will determine where the the texture will be reflective like a mirror (white= full reflection; black= no reflection).
So in this case you don't have to worry about that.
You don't need tutorials to create spec maps for FS, since everything is metallic

What I usually do is grab the difuse texture, raise the contrast (levels in photoshop), apply a small noise and voila. Sometimes I have to reduce the saturation a bit after all that.
But the rule of thumb is, in the spec map, the brightest a pixel is, the more shiny it will appear in-game... don't fall in the error of doing grayscale spec maps though