A couple of thoughts. First of all, when I built my little winter coop, I only made roof overhangs on the front and the back, and I wish I had built overhangs on all four sides. I have a little leak in the roof where the rain comes in where my roof meets the wall on one side. It's annoying, and I can't quite find the actual spot where the rain is coming in. I can't really see how you've designed the roof on your coop (drawing is too small), but I would be very careful with a hinged roof that you don't build a leaky one, too. My real question about the hinged roof, though, is why? Your coop is 4 to 4 1/2 feet deep, plus it's on 16" legs; you aren't really going to be able to reach in there much unless you're very tall or stand on a ladder. How's that going to work?
I can see the coop is 6 feet wide, but I can't see the length. If it's not much more than 4-5, you could build the front wall so that it completely opens (two doors, opening from the middle). This is what I did with my winter coop (picture on my BYC page) and I love the design. It makes it very easy to get to the inside of the coop for cleaning, etc. I put a board on the bottom front to contain bedding, but it's removeable so that if I want to sweep or shovel out all the bedding, I can just push it out without having a permanent lip in the way.
Don't forget to cut your popdoor a bit higher than the level of your bedding (this is one I forgot).
Try to build in at least one square foot of vent space per chicken.
Consider that any opening on your coop will need to have raccoon proof latches, too. If you build a sliding door on the outside, that can be vulnerable to having the door ripped right off the track.