Only had a couple brief moments today to work on this: in the morning as my wife fixed breakfast, and again this afternoon after I'd done the grocery shopping. Managed to cut holes for the windows along the back wall and install the windows, and to make and install six more window frames (without the transparencies) for the interior. Pics to follow.
Had a little over an hour in the morning. Treated some trim pieces with CA glue, laminated and cut openings in one entrance, added the round and rectangular windows, then dry-fitted what I had so far.
NOTE TO THOM: slight correction needed -- the door on the wall with the round window needs to have the trim added around the rectangular window and the door frame. If I cut out the white areas as printed, the holes would be the size of the door and window frames, rather than the size of the door and window. My window sub-assembly nearly fell through the hole.