It’s kinda hard to see in some of the pics, but if their feathers around their necks and tail are round it’s a hen. If they’re pointed it’s a rooster. They call them saddle and hackle feathers.:D
You can keep ducks and chickens together just fine, but it's best to keep them separate because bullying can be a problem and ducks need a little different diet. :rolleyes:
I would recommend getting at least two ducks. Ducks and chickens will get along, but they are different species. Also, ducks are very social animals so it he would probably like someone else like him around. :D