The models come in MAX, OBJ and FBX formats. The additional formats only have a basic material setup.
The trees use two submaterials. Texture maps include diffuse and normal maps in 1024x1024 resolution, and the branch material has additionally an opacity map that can be used to control translucency or SSS amount.
The trees are modeled to real-world scale in millimeters. If you're using the imperial system you may need to rescale the models accordingly.