I am writing a book, and found information in another book that I would like to reference or use. The information is on child development. Do I need to reference this other book? how do I reference it? do I need the permission of the other author to quote her in the book? Can I paraphrase her and then not reference her? What are my options for using the material from this other published book?
I'm not sure of the legal aspects, but it's a good idea to give credit if you quote or paraphrase something. Partly that's courtesy. Partly it's making sure your readers don't mistakenly give you credit for ideas you did not create.
But credit is only one reason to give a citation.
Here's another: It helps your own readers research the topic more deeply if they're interested. If you got useful information from a source, some your readers will want to follow up on your citations in order to enrich their own understanding.
As for how much you can quote, I'll leave that to people who know more than I do.
You don't need to ask permission, but you should always reference even if, perhaps especially if, you paraphrase. Otherwise it is plagiarism, pure and simple, and one of the worst sins you can commit in writing. Wikipedia has a pretty good discussion on the doctrine of fair use here Fair Use