When you use wire in a collar you want to sew in in place. You can see this in the Red Queen white collar.
I've never seen a coat pattern like that. Your more then likely going to need to shirt pattern that is designed to have a middle seam/button up and work from that before making modifications.
Just to make thing more interesting the also gave him puff sleeves.
Maybe this as a base pattern. But the sleeves are not right for him, since it puffs then tapper to be skin tight.