1. Does the book assume you know Java well enough? Or does it teach Java too?
No, it does not teach Java. There are so many Java books, tutorials, and the like out there, it seemed superfluous.
2. Does the book assume that the reader has done mobile development previously?
No. It does somewhat assume you have done widget-based GUIs before -- Swing, SWT, .NET, MFC, just about anything other than low-level HTML/CSS/JS based GUIs.
3. What is the format of the book?
PDF, Kindle, or print.
Does it assignments and exercises like a text book, or is it more of a "hands-on" format book?
I would have to say "neither". I am working on
Android Programming Tutorials, a follow-up book, which is definitely more in the line of exercises. Version 0.5 of that will (hopefully) be available to subscribers in a week or so.
It would also be great if we could have a look at the table of contents, or an excerpt
How about
this and
this?