Some advice that I hope will help (and others can qualify based on their own experience): Modularity is important, but having connected pieces in UDK will save you a lot of trouble and generally works better. Try combining pieces and having multiple variations as distinct static meshes that use the same texture/material. A…
I'm not really sure what's wrong there, but what might help you out is to use a simple roof mesh and use normal/height maps for the details/forms. It's a lot easier to manage very low-poly assets, probably bypass some of your current problems, and since you'll probably want some bump detail anyway you might as well take…