I wouldn't put all these details in one texture.

Also, I think that you should strictly make a difference between characteristics of the surface - which should be in the texture, and its alpha channel - and assets or objects, bigger edges and more prominent forms - which should definitely IMO formed within a 3D modeling tool to get a realistic height map and normal map.
And for the glossyness - not sure whether this is the right word - you should draw an alphamap.

If you wanna achieve the realistic first person shooter a-like look you should definitely go that way.

If you want to achieve more cartoony and painted style, then you should avoid the hard edges, and add more color to everything.