Thank you, as always this is very good advice.
The lock is on the run door not on the hutch - I have it to keep my birds safe at night and any time no one is home - I had a friend lost some chickens to a fox (or foxes?) which managed to work open the latch and a bolt on her coop and opened the door. Predator proof/predator resistant latches and bolts are so expensive over here so to keep the cost down but security at the highest we have two hasp and staples (one on top of door, one on bottom) which are padlocked and we have a brenton bolt in the center of the door.
We haven't yet put the new coop together because I wanted it all painted first to make sure we got into all the nooks and crannies, so I don't yet know if the nests are the same level but judging by the picture, I think the nests are higher than the roosts.
I don't have a problem with poop on eggs because between cleaning out and completely changing the bedding (which I do twice a week) I poop pick every morning as soon as I let them out - I do the whole hutch ducks area as well - I use a poop scoop which works by letting all the unsoiled bedding fall through the slots and the soiled and wet bedding along with poop stays on the scoop, then I replenish as needed, so they always have a clean bed to go into.
We won't be using the roost bars provided because they are very slim, - so we are going to buy some 2 x 4's and make the roost bars ourselves, do you think that is the right size?. Our aim is to have them sleeping in it by Tuesday night, will post a pic when coop is done