That is a crazy number of chickens!! How are you going to freeze all of them.
With your egg layer chicks- I am very careful the 1st 2 weeks and make sure the temp in a couple of areas is 99 I use 2 red lights for about 25 birds. Make sure they have a shade area to go to as well.
After the 2nd week I raise the light an inch about every 5 days until they dont need it anymore.
Have you ordered chickens in this number before?
You must have a large facility.

Sorry forgot one more thing.
You do realize you cant keep them together in the same brooder right?
They must be fed different rations. Meat birds get starter feed then finishing feed-much higher in protein. I give my egg layers chick mash then wein them onto layer pellets.
Your meat birds will be ready to slaugher in 8-12 weeks where as your egg layer may be ready to be without a light by then.
They do sell brood guards that will keep them seperated (and draft free) for a very short time but these are not birds of the same feather by any means.

I raise up 25 broilers and several new laying hens every year. I keep them all in the same brooder feeding broiler feed until I have the broilers dressed out between 10-12 weeks. By this time I've moved them into a chicken tractor, which the young pullets stay in until they are old enough to be introduced to the rest of the flock. I try to get my chicks first of May so it is usually warm enough to move all to the outdoor chicken tractor by June here in Michigan (might still need a light for cool evenings). 200 birds is alot, you must be going to sell them? You'll likely need several brooders/tractors. NH'ers make nice laying hens - the roosters can be a bit mean. I raise black australorp hens with one mild mannered black aussie rooster.

Once the Cornish X's are feathered out and the nights are warm enough, they will all get moved to their chicken tractors with their yards surrounded by electric mesh. As far as feed goes, we don't feed our meat birds "starter" but rather just take them all the way through the 8 weeks on a Certified Organic feed.

Maybe I should call the hatchery and see if they can't give me another breed of roosters though. I don't want mean roos.