Sometimes cockerels do not ever get along. You never know.
You would need a second pen for one of them or re home one. It is tough though since they are usually your favorite chickens
You might need to keep them separated for a while. If they are not drawing blood, they may be fine though. It can take two weeks for them to integrate completely
It does not take too long. They do not have oil in their feathers like ducks so if they are in a pool, you need to be there to get them out. I would not do it though.
There are misleading videos out there that show people swimming with their chickens.