Sounds like you have a good plan in the works, your chickens will thank you with lots of eggs.
I don't see the point in a low vent for winter as moist air rises on it's own because it's lighter than dry air (tis why we have clouds up high).
JT
Looks like a 4'x 8' coop... I'd drop the nest box down so they won't want to roost (poop) in it. Fasten some U shaped pieces of plywood to the wall and put your roost(s) in there so you can remove them for cleaning. I'd skip the linoleum and just put 3-4" of pine chips on the floor.
While your...