So i recently picked up blender and i'm having loads of fun. I just finished my first project which is the house i grew up in:

http://imgur.com/a/qTzm0

.blend file

it took me four tries to arrive at a result that i'm sort of satisfied with. i'm saying sort of because there remain some issues as you can see in the picture: the roof and base are shaded smooth which results in weird shading artifacts to the right of the stairs and in the top right of the roof. these are shadows on flat surfaces that i cant get rid of. no amount of triangulation or cleaning up of the mesh removes this. i have opted to shade the whole object smooth and marked selected seams smooth. is there a better way? any help?

also if any of you cracks would care to take a quick glance at my mesh and texturing, i'd really appreciate some pointers where i did sloppy work or used bad practices to avoid them in the future.

thanks in advance!