I thin that as with anything, there are differing opinions on these things. I know that as a human nursing an infant, my water intake did relate to my milk production. It also made me urinate more.
Now, I am very inexpierenced with chins, so this is purely speculation, but if you wanted to try a bit of unsweetened juice to encourace drinking I would think it would be as little as possible to give the slight hind of fruit. I may even think about squeezing a fresh apple a bit vs juice....or even just infusing the water by letting the apple sit in it.
A small capfull of bleach in a sink would serve as a disinfecting bath for the water bottle and its parts. It has to dry completely before you can refill it. I have extra bottles on hand to switch out.