rbratt,
If you are sincerely seeking truth about the KJB over modern versions, then you will do two things:
1 ) For your concerns about variations, continue reading your Bible, noting especially the places where the NIV differs from the KJB in meaning or by omission, and ask yourself why.
2 ) For your concerns about the history behind the KJB, read a good book that covers this topic. Here is an excellent book to start.
http://av1611.com/kjbp/books/review-cwg.html