Is there a reason for the slant?
You could run all roosts straight across at one level.
That makes less fighting for the "highest" roost.
If the roosts are only 2-3 feet off the floor, the chickens should be able to get up and down just fine, without needing lower ones to use as a ladder; but...
Brooding chicks is a lot of work. I prefer to get it over with all at once.
Big brooder? Well, yes of course.
The most chicks I've done in one batch was 125. They were in a chicken house 4 x 8 feet for the first few weeks, then moved into a 12 x 12 foot space. They lived there until 8 weeks...