I played around a bit with those models.
I have to concur with AsioAsioAsio - those Sketchup models are not well suited for the game... Better use them for reference.
They can be converted - if there is really demand for it, i could write up a tutorial - but it will be not too basic - to much stuff to cover.
Anyway... as a byproduct from my trying arond i made two models more or less game ready - cut the polycount and converted the textures.
Around 500 triangles + 256" Texture each. (From the original 6000+)
I did not exported any buildings so far, so i dont know what settings will work nice (How about a tutorial ? @Asio

Does not need to be fancy or detailed - i just need to know good settings for shaders and how to make the Nif's game ready (Merging to other nif in NifScope ?)
My experimantal nif's + Max sources if you need to reexport are in the archive.