Hi Noobster,
Don’t know if your still around as I’m 4 months late but, I can help you out adding your models into the game.
As for what Train Fever can handle I’ve used this post from the dev’s as a rule of thumb;
http://www.train-fever.com/2014/05/facebook-page-and-development-insights/
though of course the game can handle higher detail, but then lod’s are a must.