I know, love, and understand Cochins. They are not only docile, but slow, as in plodding, and naturally lazy, but endearingly so. If one is in a certain position for very long, she will be reluctant to move. They are the turtles of the poultry kingdom.
Very recently, I had to give my Black Cochin Morgan a warm soak when she was gearing up to begin laying after molt because she was acting like she was having trouble getting the first egg out. She settled down in the pan of warm water and was in no hurry to get out or it was just too much effort to move.
If you view the mating ritual of Cochins in this light, then a Cochin cockerel taking his time on a hen really isn't that out of character. Neither is a hen continuing to lie there on the ground afterward. As for her actions on the perch later that evening, what you observed may or may not be directly related to the mating earlier. Like you mention, she does bear observation.
Your eight-month old cockerel is only just embarking on his rooster career. His activity is especially intense beginning now and will continue in this vein over the period of the next year, at the most. Then he will probably settle down considerably. Many poor, over-enthusiastic young cockerels manage to so outrage the sensibilities of their keepers, they usually get themselves terminated before reaching the "mellow" age of 18 months.
Therefore, I recommend segregating your Romeo if you are worried he's too hard on the hens. I find this a very satisfactory arrangement, and it pleases the cockerel, too, as long as he can still talk to the girls through a fence. If you can be patient for a year and then put him back with the girls, you're likely to see the boy has matured and toned down his act considerably.
. He does a little dance in circle with one wing dropped and they squat. Simbad's the man! As for the other two, better off without them. Again, depends on the roo. He has his place in the flock.
