Good build.
Agree on the need for more ventilation, it is actually more important in the winter than in summer in cold climates. I would suggest you run the roost along the back wall higher than the nest box entrance, make it at least 12" from the wall. Then put some low openings on the pop door side so fresh air can come in low and the "old" air can (via natural convection) go out the upper vents you are planning to install.
That chip board NEEDS to be waterproofed or you are going to have a lot of mold and a rotting floor. I've seen people post that they use a product called Black Jack.
And x2 on the chicken wire. Coons can reach through it and rip a chicken's head off. It is also very weak protection against canine predators.