The IDA Pro book is all about IDA usage. There are some tips about disassembly in the book, usefull to help progress in reversing but it's absolutely not a book to learn assembly language or reverse engineering.
I think you have to learn almost the basics of assembly language and the basics of the environment in wich you plan to research vulnerabilities. For example if your target is Windows and Intel, Windows SDK and probably C language. Although you have to learn the processor architecture because for example with x86, the processor instruction set is just a little part of what the processor offers to developpers and you have to understand the IA32 or IA64 architecture (memory management, protection, interrupts & exceptions, task management, etc). See the system programming guides there : http://www.intel.com/content/www/us/en/processors/architectures-software-developer-manuals.html
It will be more productive to read books like "Assembly Language for x86 Processors" to learn assembly language, and books like "Reversing: Secrets of Reverse Engineering" or "Practical Reverse Engineering".
Try also to write some simple assembly language programs to understand instruction set and how program flow control is implemented in assembly language (loops, conditions, etc).
Although it's not about vulnerability research, consider reading "Practical Malware Analysis" book first. It can help you like parts 2 and 3 are very valuable to learn how to analyze and understand a windows binary. Note that chapter 5 is a little IDA Pro book ! This book is very well written.
It's a long but interesting journey !