New to Chickens, Coop, Fence advise

[aart]

For ventilation, I'd really want to open up some of that triangle of space above the human door, as ventilation up high is preferable.

Yes.
I'd also extend the roof overhangs so you can have open soffit venting all year around.

They'll go in at night on their own.

Once they are 'homed' to the coop, which means keeping them in the coop for a few days before allowing out into the run or free ranging.

Another thing about that coop design is the nest access, better to have side access to avoid the common top hinge leakage issue.