Triangles may be difficult to avoid, but not impossible. There are several techniques to do so. Search the forum for them. In particular, I remember a thread called something like “modelling techqniques” in which such things were discussed. It’s OK to have some triangles in places where it’s not easily visible BTW, should you really need a few.
Before you work on the material, I’d suggest you pay close attention to the mesh first. For example, you first have to make it a subsurf mesh, and make the nesessary changes to make it look right. Just enabling subsurf will most likely not work properly. Also, an interiour would be nice, but you could cheat that by having black windows (although you’ll feel better about the result when you don’t cheat )