Coons have been my nemesis. If you get a horrible attack at night, where birds are torn apart - those are coons. You need to trap the coons. Once they find you, they will be back. Once I got a note: "please leave BBQ sauce, we are getting tired of them plain." jk
They can crawl up anything, are incredibly smart, can figure out simple latches, and can go through chicken wire like nothing. If you cannot build a Fort Knox run, then you HAVE to lock up the coop every single night. I tried the automatic doors - what a wreck that was, as in the coons got in, and could NOT get out. Nothing was left alive.
Ventilation is incredibly important in a chicken coop, but that is also the weakness of the coop. If there is an opening, a coon will be testing it out. Over and over again.
Not all roosters are great roosters. If you have a great rooster - I have found that they do help against day time predation. However, they are no defense against coyotes. Coyotes are just bigger, and in the spring are teaching pups, and working together. Roosters are also no defense against coons in the dark. Chickens are rather comatose when sleeping.
Mrs K