I built the coop from OSB that I sealed, primered, and painted with two coats. As you say, a simple design but it works. My next task is to build a nesting box on the back end with a hinged top. Then I can extend the roost rails to the other side. I think I may change out the round dowels with 2x2's that I can drop into cleats on the sides and middle bars. I've been told that smooth round roosting rails are hard on their feet and they prefer something flatter, hence the 2x2's.
No, they're Gold Comets which I believe may be a hybrid of the RIR and something else. Great, Great layers. I get 17-19 eggs each day and they're all large to jumbo size. There's 19 of them I bought as 'started pullets' at 17 or 18 weeks old. We started last spring with six, then another six, and then seven. There was supposed to be six but somehow seven got in the crate when I picked them up. The last group, the 'Youngsters' all just started laying in the last week or so. We'll probably make it an even thirty or maybe even thirty-six next spring. My coworkers are all lining up outside my door in the morning to buy free-range organic eggs.
My favorite thing is to hang a head of lettuce from a string in the middle of the run and they make a lettuce pinata out of it. It's not a pretty sight when they go at it.
Pigs with feathers!