some of the nipples will work up or sideways. I however found my chickens will get water but some still falls not a leak but chickens not getting all the water they pecked. I added a feed trough with silicone seal to catch the extra. If you see wet chips don't assume your nipple is leaking. You could add a small funnel under the nipple with a hose that goes outside for drainage (if you have trouble as they get older).
its cute. mine only concern, would be rain. do you get alot of rain. that is a ton of windows, natural light will be awesome. what are you planning on putting over the holes, and using for windows? plexiglass would work good. imo
also i read about the nesting boxes on the outside, so egg retrieval would be easier. great idear. good luck and have fun!