Re: Water...When and how much?
I think the reason you're having trouble finding definitive information on when a baby needs water is because there isn't any. No-one has done the studies.
Most moms introduce sippy cups with water in the second half of the first year. Both my kids got water sippies with meals by around 9-10 months, and it did not hasten their weaning at all, since DD1 nursed until age 3 and DD2 will probably go at least that long. I personally would start offering your LO a sippy now, with meals, and allow her to master that new skill. She'll probably continue to choose nursing when she's thirsty- breastmilk is yummy and water is... Well, water! But as she goes through her second year, there will be times when she'll drain the sippy and nurse, too.
We talk about baby-led solids all the time- I think a baby-led approach works for liquids, too.
Coolest thing my big girl said recently: "How can you tell the world is moving when you are standing on it?"
Coolest thing my little girl sang recently: "I love dat one-two pupples!"