Ask HN: Would you like your favourite celebrity read a book to you?

I'm working on a product where you can select a book, and a voice you want and I'd read out the book summary or review in that voice. Imagine Barack Obama or Morgan Freeman reading your favorite bedtime stories!

My questions are

1. I'm unsure about how to make it a good and useful product. What are some of the usecases? I can summarize blogs, books, etc, but what else?

2. What are the copyright implications here? Can I just take someone's voice and use it?