Dry fit exterior walls interior

This picture shows roughly what the interior layout will be. The fake walls on the right: the first one won't go all the way to the back of the house. It will stop 4" from the back of the house, creating a short hallway. The first room in that section is the bathroom, with the small oval window. Then the second fake wall will go all the way to the back of the house and will have a door right up against the back of the house, leading into the end room, the library. The large opening will be french doors out onto the porch. Both these rooms will be repeated upstairs only the end room will be the master bedroom. I am toying with the idea of a circlular metal staircase in a corner, going up from the library to the master bedroom. There will be a fireplace in both the library and the master bedroom and that big, full length chimney on the outside of that wall.