Good luck with the black hole you've just entered.

Building textures are generally 512x512, bigger buildings can be 1024x1024 and really large and deatailed buildings can be 2048x2048, but that should be avoided at all cost.

CloD doesn't use PBR as of now, but buildings will have diffuse, normal, specular, and alpha maps. Diffuse and alpha will be in the same dds (diffuse as file, add the alpha into the alpha channel you create via CS). Normal and specular will be in the same dds (normal as file, spec added into the alpha channel you create via CS).

Delete all unseen polys.