Your chicken building should always contain a perch. When building your chicken coop the perch should be made like a ladder, sloping back to the wall and with enough space between each perch to keep the chickens roosting above from pooing on the chickens on the bottom rack. You can put the bottom perch any distance from the floor, two feet or so. Make sure there is plenty of room for the birds to roost without being too crowded.
You can hang your waterer and feeder from your rafters and that will keep them from pooing in the water and feed, plus they can not dig out all the feed to get to the stuff they like best. Most chickens like things like watermelon rind and veggies too, so we always gave those to our birds as a treat, they will pretty much peck a rind till you could read the paper thru it!
If you have a lot of chickens, you may want to buy lice dust just in case wild birds give them lice, that’s a mess to get rid of and the lice will get on humans also.
Oyster shell for grit and calcium and a good chicken feed is about all you need for feed. They love green grass also, so if you have them in a lot where there is none, you can take grass clippings, ONLY FRESH ones , and give them those too as a treat.
Chickens need a safe place from predators so make sure nothing can get into your chicken coop. Even a 2 inch hole will let rats in and we lost some chickens to raccoons who found a 4 inch hole in the floor, still have no idea how on earth the raccoon got thru the hole , but he did!
Good luck with your chickens and your chicken coop plans, fresh eggs are great!