Wow, looks like a professional job, wish I had your carpenter skills... Yeah, you'll eventually need to separate out the turkeys (or eat them), but that will leave plenty of room for your chickens... As to ventilation, very important as others have noted, but easy to add to wood construction... But study up before you go adding random holes everywhere (you can even add a solar fan if you want to get fancy) and remember you will need to be able to increase it for summer heat and decrease it for winter... Drop downs work as will sliders and even strategically placed drilled holes. Some people use those globe like finned things on the roof.
