No, there should be no need to move Orion to a separate cage. If there are obvious signs of stress in any of them such as loss of appetite, weight loss(other than normal seasonal weight loss), lethargy, diarrhea(or any sudden or obvious change in stools that cannot be directly linked to diet), vomiting, teeth grinding, pawing at the mouth, or any other unusual symptoms. If one of them was sleeping off by himself somewhere whereas he'd normally sleep in the hammock, then I'd start to be concerned. If Orion won't let one or all of them in the hammock with him, or near the food bowl, then yes, he would need to be separated. The fighting unfortunately is just part of normal ferret play. The fact that the ferrets get beat up and run back to get another butt whooping tells you that it is no big deal to them. Ferret play can be really violent looking to us and sometimes they really do hurt one another(one will usually hiss or bark, then bite at the other if things start getting to be too much). He may still be bullying them to assert his *dominance* amongst them. He may just be a *bully* ferret--seems like every group has one at some point.
The cuts and scrapes are normal. I have found scrapes and scabs on my guys--even amongst groups that never fought. They have their occasional tussles it seems. I would just keep an eye on them for now and unless you see some really obvious signs of stress(inside the cage), I would just leave them be. If it helps, you can slather a little bitter apple on the "victim's" neck to keep him from biting there(avoid putting it on any open wounds of course) OR try putting ferretone there so he licks instead of bites them.