Good questions. Let's get the title question out of the way first, this is a hands-on, how-to, book focused at adoption - hence Agile ADOPTION Patterns. That is, it helps you answer the question "what practices should I adopt given my environment" and "how do I go about adopting those practices". There are tens of books out there that answer "what is" Agile development, but precious few that tell you how to get from wanting to adopt Agile to the point where you are successfully practicing Agile and getting the business value from it.
Now, as for convincing management, it really comes down to speaking their language and knowing their priorities. The language of business values and current pains or smells.
Check out the freely available chapter 5 on InformIT to get an idea of what I mean. Furthermore, each patterns starts with a description of the business value it delivers, therefore it helps you decide/convince which practices are good for your given context and your organization's goals (and hopefully this coincides with your manager's goals).
Amr Elssamadisy<br /><a href="http://www.amazon.com/Agile-Adoption-Patterns-Roadmap-Organizational/dp/0321514521/ref=pd_bbs_sr_1?ie=UTF8&s=books&qid=1220909336&sr=8-1" target="_blank" rel="nofollow">Agile Adoption Patterns</a>