Wow , you're gonna have your hands full for a while it seems . You'll have a few weeks incubating and then a few more weeks after they hatch so still some time to work on your run . Yes on the hatch thread , it will be exciting following along .
I agree its because there is no door yet . You have pretty good over hangs , they should help keep any water from blowing in up high . Once the door is up you'll know for sure .
Your roof will be fine with tar paper as an underlayment , Thousands and thousands of roofs were and probably still are being installed without ice shield . I only mentioned it because I was going to use it if I went with shingles . Its just another of those extras you could use but really don't...
Ice shied is a sticky backed rubber like membrane usually put in place of the bottom run of tar paper , it protects the deck from ice pushing up under the lower courses of shingles . It a very good product and its also kinda pricey. Here is a link to one brand ...
Shingles will be just fine . My original plan was a shingle roof because I was not going to special order metal panels , went with metal because Lowes stocked it . For my roof shingles with decking and ice shield would have cost me about $50 so it was almost a wash .