The only thing *required* is a roost and generally, a nestbox. Though they'll lay in a corner somewhere, the roost is all they REALLY care about. If there is no roost, they will not sleep in the coop, so see that's all that's *required*
Everything else is optional and for the chickens or chicken-owner's comfort. I'll let you in on a little secret, chickens are not picky
Pine pellets, pine shavings, straw, hay, sand, etc are all popular bedding materials - depends on the owner, some even use pine needles or shredded paper. The only "no no" is cedar shavings.
My feeders are generally out in the run, but in bad weather climates most people keep their feeder/waterer inside the coop - depends on the owner.
Suet cages and treat stuff is mainly for the chicken's entertainment, especially useful during inclement weather - depends on the owner.
The use of dropping boards and such are dependent on the design of the coop, which depends on the owner.
You practically can't go wrong. If something isn't working to your liking, try something else, the birds won't mind too badly.