It's not quite the same as locking them in around the clock (which works great on adults, chicks are a little more iffy, though it's worked for me), but if you don't mind potentially needing to herd them in the evening that's a perfectly acceptable way to do it. They will eventually learn...
The 17 sq ft includes the nests, which you don't want the chickens in. So actual floor space is about 9 sq ft. That may be an issue down the line, but let's look at ventilation first.
Unfortunately prefabs are notorious for lacking in ventilation. I assume that's not an actual ridge vent on...
Ventilation means having predator proof, open air flow inside the coop - in hotter climates it's vital to provide as much as possible, around 2-3 sq ft per bird, 24/7. Has nothing to do with the run space, unless you're saying it's an open air coop run combo where it's a single open space?
^...