Alex, get that fine looking nest box in there pronto!
It is the nest that the pullets treasure. If it has eggs in there, that's fine too but an egg kicking around on the coop floor is just some odd, oblong thing to them

. There is a danger that it will break and the chickens will eat it. That could lead to
baaad habits

.
It may not take much convincing to get them in those nests but if they try to build a nest elsewhere, do what you can to discourage them. Yes, they are all likely to want to lay in the same nest but that's okay. A nest that amounts to a little depression in the corner of the coop may not get the same respect as a nice, comfy nestbox and, once again, they may treat an egg found there as tho' it is food . . .
grrrr!
Not only is it good to keep them from roosting on top of the boxes but it should be absolutely forbidden for them to roost
IN the boxes! No fouling the nests and that is exactly what roosting birds do . . .
Once they are comfortable with using the nests for the proper purpose, you may want to hang something like burlap over the front. A hen intent on laying is perfectly happy to push her way into a dark nestbox. She isn't likely to want to roost in there in the dark. When the eggs are laid in the box, they won't be seen. Bad habits once again are avoided. If I remember right, you don't have a rooster. Some of those
jerks can be big trouble when it comes to egg eating but any
feather-brained chicken can become a deviant

. Keep 'em on the straight and narrow.
Steve