Wonderful house. Wonderful price! I like that you covered over the nestboxes with an extended roof as blowing windy rain can leak into those boxes. It's one of the reasons we opted for a design with a drop door nestbox access. We had an idea to put shallow plastic pans at the botom of each nest to keep the straw dry perchance any water ever got in. After 3 years of using a tarp cover no water ever leaked in so we took out the pans and lined the bottom of each box with a piece of fitted plexiglass (one of our OCD Silkies - I didn't know chickens could be OCD but we have one - she kept scratching the nestbox bottom so hard the splintered wood injured her toes and nails).
We have the same wood walls on our coop. We never painted it because we always tarped over our little coop. However, yours is a very large housing and a tarp would easily blow off so its good you're sealing the wood as it will curl up in the rain.
We have 1" chicken wire on our little coop and it kept out a stray German Shepherd but you may want to consider stronger hardwire for the open pen if you have Raccoons, Foxes, Coyotes, or Bears? Do you have the wire going down into the ground as predators are excellent diggers. We opted to put a stepping stone patio around all sides of our coop to keep out diggers.
As you've probably come to realize a coop is like a house - it's never done. We've been working 3 years on our housing and still have about 2 more years because of $$ before it's done but firstly we opted to invest in the security issues to keep the hens safe. It's fantastic that you have electric fencing - very nice - what do you do for security when the electricity goes out? Backup generator?