...ideas for the inside for the chickens. Like maybe a bookshelf they can make nest boxes in, or chairs? Any and all ideas welcome...
		
		
	 
Bookshelves can work but most bookshelves are not deep enough. It might work better to find containers between about 12"x12"x12" and about half again that big in any or all directions.
Then look for something sturdy to set them on. The floor will work is you don't mind bending down to collect the eggs and you still have a minimum of 4 sq ft per chicken of floorspace without counting the space taken by the nests. Chairs might work for that.
This link is a very old thread that has lots of ideas for creative nest boxes. If you want to go very simple and/or practical, that is okay too. The chickens won't care how creative the nest boxes are.
They need roosts, nest boxes, waterers, feeders, grit cup, oyster shell cup, and open floor space (even if the coop is used only for sleeping and the nests).
A poop board under the roosts works well but isn't essential. A storage area is very nice. So are double doors so you can walk through one, shut it, then open another one into where the chickens are.
If they might have to be in the coop for more than a day or so, like for a severe storm, then a place to take a dust bath is good.