Well it is most likely a rooster if it has been making rooster calls.The tail feathers look like it is a rooster.So I would say a rooster.
Have fun with your roo,
jeetthemeet
For the nesting boxes place eggs/golf balls in the nest as a decoy for your flock. As for the roost, they should find it naturally but it may be to high/low. Make sure the roost is higher than the nest boxes.