Are you sure this "Abuse " isn't just mating? Feathers missing and bald spots can be caused from a variety of sources. Are your birds molting? Are the infected with lice, fleas etc.? These parasites damage the feathers as they are developing and cause them drop or not develop properly. The parasites can cause developed feathers to fall out.Do the hens need sprays/dustings to control the vermin?
Pecking order? To establish dominance over the other hens, they will peck and abuse weaker members of the flock. Once a blood spot from the pecking appears others will join in and eventually kill the bleeder. Finally they will often feast on the corpse. Are you sure it isn't the hens that are abusing the other hens in a pecking order ritual?
Are your hens receiving the proper nutrition? If the feeding is unbalanced the hens may be losing feathers to malnutrition. They are in a pen. They can't forage for insects, worms etc. You are controlling what they consume.
The rooster crows in the morning as a call for his hens to rejoin the harem after being dispersed or scattered the prior evening. Of course he is mournful as he tries to collect his flock and is locked outside the pen.
Are you sure the abuse isn't yours rather than the rooster's? He can't delouse them, he can't get them the proper food, he can't change their environment. Are you sure his abusing them and not just mating? Are you sure it isn't the other hens that are abusing each other? If you see it, can you separate what you observe from what you think?
I'd check out the potential problems first and rectify them. I'd return the rooster to head his flock and observe what was going on. Then I'd make a decision on my observations.
Your hens wont stop producing eggs. They just wont be fertilized. Do you know how to keep them producing through the winter? If not, don't blame the rooster. I'll be here to answer that one too.