Short answers, pulled from the story.
Einstein agreed partly to help his co-author Leopold Infeld financially. Infeld had failed to secure a permanent position at the Institute for Advanced Study in Princeton, and the two agreed to split the royalties from a book that Einstein's name would virtually guarantee would sell.
Einstein argues that belief in an objective reality, meaning a real world that exists independently of the observer, has driven every major advance in physics. He defends this view against the probabilistic interpretation of quantum mechanics, which he accepted as experimentally successful but philosophically incomplete.
No. According to the New York Times review, not a single mathematical equation appears in the book. It was written for readers whose mathematics went no further than multiplication tables.
The book has four chapters: The Rise of The Mechanical View, The Decline of the Mechanical View, Field, Relativity, and Quanta. Each chapter traces a phase in the development of physical ideas from Galileo and Newton through Maxwell and Einstein to early quantum theory.
Einstein defends field theories as the most promising framework for physics. He suggests that matter itself might be understood as regions where the field is extremely strong, rather than treating particles as independent objects separate from the field.
Cambridge University Press published the original edition in 1938. Simon and Schuster published it in the United States.