What is more important is that they get some perspective of distance and changing scenery. I used a weed fabric, very see through and made a run in the porch about 8 feet long and 2 feet wide, they could see me approach or the dog or cat. I also made an obstacle course for things to climb onto...
It is not a good idea to introduce chicks to a flock of established hens. You are setting yourself up for heartbreak. Without a broody hen to protect them I would not introduce them until they are large enough maybe 5 months old to have a chance and even then would introduce them in a neutral...
I have experimented with this too, and found the following really helps them sleep for night cycle and be active in the day.
I would turn off the heat lamp for about an hour, the chicks would cuddle together in a corner and sleep in the dark, I would then turn on the heat lamp again but they...
Check the temperature in the brooder, sounds like it may be too hot for them to cuddle together. That may be why they are spreading out to the far corners to adjust their body temperature. Purchase a thermometer and put it at the bottom of the heat lamp on the floor where the chicks are.
My pullets just started to lay at about 23 weeks, not all are laying yet. When exactly will a hen go broody? Can a young hen go broody or are broody hens typically old hens? Is there any chance I could get a broody hen this spring?
I also bought some young Buff Orpingtons based on what I read about going Broody and being Good Mothers. The guy I bought them from straightend me out saying 1 in ten of his would go broody. So now I am hoping at least 1 of the 4 I bought will go broody. I guess we will have to wait and see...