I can give a few suggestions that have worked for me.
For roosts. A picture would help, but with the dimensions of your coop, is it possible to put a roost across the 25"...which would be at one of the ends. I'm not sure how this would work with cleaning underneath. I use fence posts nailed onto 2x4s that are set against the wall. They entire roost can be moved. Although for you I wouldn't use fence posts, although you could. I'm meaning more this idea, except only 2 feet wide and 3 feet high with 2-3 roosts. You can probably get all the chickens on it.
1) White arrow: To the left of the pic are roosts leaned against the wall. Easy to move, easy to manufacture.
2) Red arrow: In the middle of the pic is an old broken step ladder I refused to throw away because it looked too handy to toss. He cut the broken legs off and cut the other side level. The ladder makes a great roost!
3) Green arrow: The section of good length he cut off makes a great side roost.
#2 or #3 would probably work well in your coop. If you could find an old step ladder someone's throwing away and either cut a side off for roosts or use the ladder parts.
Or perhaps you could have 2x2s cut to fit across the 25" width part. That should accommodate 2 roosts for sure, maybe three. A 2x2 is very inexpensive. Just make sure the corners are sanded round. I've got two small coops for separating breeds laying/setting hens. They have a roost is the length of the coop. Maybe that could work for yours. Or perhaps your roosts could be across at one end. Or both ends.
For my first year I used plastic wire and step-in posts to make a pen.
Please note this is not secure for predators, but it worked for me because it was right in front of the house. It worked until we got something better put up...lol. It worked for the chicks and for them as adults.
In canada, the roll of plastic wire was 50' for $20 on sale. Plastic step-in posts are $2-$3/post. A 2x2 is a couple of dollars and a wrecked step ladder would be free. If your chickens seem happy and aren't pecking each other, you are probably fine for right now as you set something better up for them.
I also use height to my advantage. I use bales in my coop, but I don't think yours could accommodate that. I like the idea of putting your coop on stilts if that's possible. That adds instant space. There are some good posts prior to mine as well.
