Definitely block off the bottom because it's not really tall enough for chicken use but it's definitely attractive for rodents to nest. I'd put a cheap vinyl flooring inside to make it easier to clean out. The door being open and having the screen door is great for ventilation in the summer, but you also need good ventilation in the winter. The little vent you have is not nearly enough. Consider cutting a big triangular opening in the back near the ceiling and covering it with hardware cloth. Get an automatic chicken door and install it (takes about 10 minutes). Do not get the cheap plastic one. Spend the money for the metal one so it lasts for many years (although it might need a battery change). Don't forget to think about roosts. 1'/bird. Place them higher than the nesting boxes. Make sure they have a way to access the roosts and make sure the roosts are a good 15" from the wall or the wall will be disgusting daily. Chickens poop all night long and the poops are not dainty (not even bantam's poop is dainty). Storage for feed - you need a bin to put it in. Rats and mice chew through the bags. Heated waterer in winter if you get freezing temps, and a large enough one in summer that you can put frozen jugs of water in it to keep the water cool. I use a 13 gallon Rubbermaid trash can with drink cups attached in the summer. My coop has nesting boxes that I can access from the outside in case I just don't want to go in. The boxes open from the side rather than the top in order to keep them weather-proof. 1 nesting box/4-5 chickens is all you need. They often have a preferred box and I've seen where several will be in it at the same time. My feed boxes are buckets with pvc feeder tubes. I attached a picture of the feeder tube. You can get them at Tractor Supply, D & B Supply or online. The chickens stick their heads in to eat. The feed stays clean and there's less waste. Using these methods I can safely go away for a week. I use baseball netting over the free range area because of hawks and eagles. You can get a 4' x 100' roll of black hardware cloth from a company called Landmark on Amazon for $180. You need 10' minimum of run space for each bird. Plan for chicken math! Your coop is looking good!