Welcome to the forum!
It is time for me to understand what is going on under the hood. What's the best book out there to understand everything I'm seeing in F10 Explain Plan?
Why not start with the free information that is available on the web?
Maria Colgan is a member of Oracle's development team that actually writes the optimizer code. She has written many articles and blogs about how the optimizer works and how to understand explain plans. What better source that one of the people that actually write the code?
See the white paper titled 'The Oracle Optimizer Explain the Explain Plan'
Maria references that article on her website at - https://blogs.oracle.com/optimizer/entry/explain_the_explain_plan_white
And see Maria's article about 'Displaying and reading the execution plans for a SQL statement'
You can ask questions of the optimizer team on that site and if you search the site you will find many other articles about the optimizer.
If you search the web for 'oracle 11g explain plan' you will find lots of references. The most important thing is to actually try the examples. You will learn more by doing than just by reading.