My youngest has been wearing a bra since she turned 7 as she's always been chesty even from birth. The oldest started wearing a bra a couple months before she turned 10 and that was only because the other girls were wearing them, other moms that I talked to had their children wearing them and the youngest was already wearing one and she (the oldest) didn't think it was fair!
As far as talking to her about life, I recommend American Girl book collection,
The Care and Keeping of You
We have used that book, on the oldest only since the youngest is too little to get all things talked about in that book. Anyways, we have used it with the oldest as it talks about getting a chest, body hair, shaving and even the dreaded period!! It talks about healthy eating, washing your face and many other things that I wish my mom had talked to me about when I was younger. The reason why I recommend the collection is it comes with a journal where she can write about her feelings as she's reading the book as well as there are some scnerio quizes that she can answer.
It has been really helpful to my almost 11 year old and something I will be doing with the youngest in the near future.
Oh and I've found Target has the best selection as far as cotton and even padded bras. The Walmarts that I've been to dont really have much of a selection that either children like. And Kolhs seems to be just the same as Targets, just more expensive.
I keep editing and re-editing, I am sorry. Kendall, you know what helped my oldest to not be so embarassed about wearing a bra? Her older cousin, who is a year and a half older, talked to her and showed fun ways of putting her bra on/off. It was like a girls time for her and a learning lesson in the process since my daughter looks up to my niece. Just another thought that helped my oldest transition from that stage to the next.
Good luck Kendall! You can do it!