I don't do poop boards but here are some pictures of mine. I made them removeable by drilling holes through the ends and the supports and dropping a big nail in there to hold them in place.
Chickens like to roost on the highest thing available, so your roosts need to be higher than any place you do not want them roosting, like nests. In the winter, I like to keep mine out of direct breezes and I have lots of ventilation up high, so I keep them below the level of my winter ventilation. In the summer or when it is warm or hot, a gentle breeze hitting them would be welcome, but not in winter when it is cold.
Ladders or the same level? Both work. There is some personal preference involved and some of it depends on your coop layout and your chickens. For example, Silkies can't fly.
Chickens higher in the pecking order will normally sleep in the highest spots if there is a choice. They can sometimes be pretty vicious about enforcing these pecking order rights. Whether or not this is an issue depends on your chickens. Some have this problem and some don't.
I've noticed that when I have some younger chickens fully integrated but still immature enough to be at the bottom of the pecking order, sometimes adult hens lower in the pecking order will be really brutal to them on the roosts. Sometimes. Not always. If those hens are brutal enough, the younger ones will look for a safer place to sleep. That might be a nest box or even outside the coop. I believe in giving them an alternate place to roost in the coop and not in the nests. Whether this is additional space at the same level or a lower roost, like you have on a ladder, does not matter as long as they can get a little separation from the brutes.
Good luck!!!
