First of all you need to secure your coop! Please do not bring any more birds home until this is done as it is not fair to the birds,this dog will be back guaranteed. Have you spoken to the owners of this dog? I would almost be inclined to shoot this animal if he comes back.
Your silkie rooster,when you say "gone" do you mean dead or missing(i am assuming dead,but just to clarify). For your girl,can you feel any break in her leg? Can she walk on leg? Is her wing dragging on the ground? You can make a splint for leg if you believe it is broken. For her wing,you could try wrapping wing to immobilize it,secure wing to body,wrap once under wing (so there is no rubbing against skin)then wrap around body in a figure eight,wrapping under good wing. Secure wrapping,but not so tight as to cut off circulation. Some recommend splinting wing,but unless you know where break is i am skeptical on how this would work. Keep her quiet/calm,give electrolytes for shock,make sure she is eating/drinking,especially drinking.
For wound on back,clean initially with a diluted peroxide solution then use a saline solution daily,apply an antibiotic ointment(nothing ending in "caine/cane")toxic to chickens. I would leave uncovered,wound will heal from inside out. For pain,you can give her a baby aspirin(81mg) or a reg aspirin(325mg)dose is 25mg per lb of body weight,crush and place in water(my preference) or feed. Keep her warm,when ill/injured birds cannot regulate their body temp,you can place a hot water bottle(wrap in a pillowcase or towel)beside her,if she needs the heat she will sit beside or on it,if she is warm she will move away from it.
Most important watch for infection,with any animal bite the risk of infection increases.