My guesses for the chicken pictures:
I think the first one is a red sex-linked cockerel.
https://www.backyardchickens.com/forum/uploads/36997_chickens_1.jpg
The second one is a silver spangled hamburg pullet.
https://www.backyardchickens.com/forum/uploads/36997_chickens_3.jpg
The last...
I am sorry to hear about your dwindling flock. It could be a dog, especially if there is evidence in the poop. I haven't seen my dog eat plain feathers off the ground, only plain fresh chicken poop. When my dog ate a turtle, I didn't know for sure until I found pieces of the shell in her...