Getting ready to do roosts in my coop soon too. If i have 12 chickens in each side, i will use 4 , four foot roosts and maybe a swing on each side. The guineas seem to like the one in their tractor.
Pretty easy. I paid $80 for mine. Might have paid less but i just wanted to get it done. Usually comes in 12 foot lengths. I am putting trim boards around the edges to keep it tacked down. Mark and cut with a sharp blade. I may use my scraps inside the nest boxes.