answer to your first question is that
Weblogic platform has different sections within it for example - Weblogic Integration, Weblogic Portal, Weblogic Server, Weblogic workshop etc.
So, when you say
you want to dive into weblogic, do select one of these sections (for eg - Weblogic Portal) first and then just refer to corresponding online oracle weblogic documentation.
there are absolutely no books available for Weblogic platform (9.0 or above) except for one book. Here is the URL of it
http://www.wrox.com/WileyCDA/WroxTitle/Professional-Oracle-WebLogic-Server.productCd-0470484306.html
this book is
NOT for Weblogic Server
beginners. This book assumes that you have sound
J2EE background and know all J2EE concepts before hand.
~ abhay