That is another thing that is easier with a really big brooder.
You can just leave the heat lamp alone in one end, and the chicks naturally spend less time there as they grow. They acclimate themselves to cooler temperatures by choosing to spend more time in the cool area. At some point, they...
There are lots of thing that can work, and different people have different preferences. I personally prefer something larger, even for just a few chicks, but I'm glad it worked well you :)
Usually no thermostat. The chicks move themselves in and out of the warmer and cooler areas. You just need to be sure they have the right range of temperatures available. (With a hen, they would snuggle under her to warm up, then run around in the cold, then snuggle underneath again.)
A really...
If you put rocks in the water, or colored glass marbles, you may not need to dip their beaks. They go peck at the shiny marbles (or rocks), and dip their own beaks, and learn where the water is. And after one chick finds the water, the others will follow their example and figure it out too.