Well, the windows are separate assets as is just about everything in the package. If you move them you’d need to adjust the walls or make new walls based on the new position of the windows. The windows can also be opened as the bottom half of the windows are separate from the top half of the windows. The bathroom window “window” can be rotated to open it. This isn’t a modular building kit, but every wall, every window, every piece of trim, etc, is each it’s own individual model. It’s a modular approach but not a complete building kit.
Regarding the props, I’ve just finished the new toilet and also added a toilet paper holder (whatever those things are called that hold the toilet paper on the wall.) Screenshots and an update will be incoming soon.