This thread has a lot of ideas about nesting boxes. You are limited only by your imagination.
Nesting Boxes
https://www.backyardchickens.com/forum/viewtopic.php?id=41108
You can keep the food and water anywhere you want. Other than keeping it dry, which is important, some things to consider.
If you keep them locked in the coop for very long after they wake up, having food and water available is a good idea. Do you like to sleep in on weekends?
If you feed in the coop, you will very possibly attract mice. If you feed outside, you will also attract mice. Where do you want them?
Many people find that if they feed outside, they wind up feeding a lot of wild birds. I sure do when there is snow on the ground. Of course, the wild birds also go in the coop for food, but not nearly as many.
If you feed in the coop, they will spend more time in the coop. They poop a lot wherever they are. You might have more a of a poop management issue if you feed in the coop.
Good luck! Hope this helps.