No reason to have the first door. It's not going to serve any purpose. You do need the pop door and the 1/2 open side is great for cleaning out. I would make the big door so it opens up. That gets it out of your way to clean (prop it up with a broom handle) but more important it is safer. The door can fall down if a raccoon fiddles with the latch but if it opens up, it will remain closed just by the weight of the door. You could build a trough (piece of plywood with 2x2 sides) that covers the bottom of the coop. that you could just pull out and dump to clean. Or just rake it out.
I would nail a board under the pop door to give you something to rest and nail the ramp to.
You need roosts as well.
Any paint will work on the roof under roofing material. Because it's made out of OSB, it needs something more than just paint. I would even take that off and start over. Add a support in the middle so it won't bow like it is now and extend the roof so you have some protection to keep the rain/snow from blowing in.