Chicks arrived safe and sound this morning and the Hay Rack Heating Pad Cave is a success. Thank you so much to everyone who helped me tweak the design and make it safe. Everyone fits under with plenty of extra room to grow. I can raise it up with stall mat remnants when they get too big for the current height.
I'm trying not to fret too much, they all seem to be in great shape with a big appetite and lots of energy. I bred horses for years so I am a big time worrier when it comes to newborns (at least these newborns can't run me a 5k vet bill

It was suggested I put a normal chick waterer in with them until they learned the brite tap. I am pleased to report that even though I dipped every beak in the water and stuck them one by one under the cave they all proceeded to run directly to the brite tap and peck away at it. They then found every single tiny crack/hole in my baracade and escaped into the larger coop area. I had to breakdown the box they came in and tape it over all the corners! They are worse than a litter of puppies!
At the moment the most fascinating thing for them to do is peck at an exposed area of stall mat. Big fun.
I am beyond thrilled with them, now to figure out who is who.
My coop is in a stall in the barn, we have wire under the floor and over the ceiling for safety. The "barn birds" that nest in the rafters are going nuts at all the chirping and keep flying into the wire on the ceiling.