On word count...
Amazon.com has a nifty feature that allows you to look at pages of a book before you buy it. That nifty feature also offers something called "Text Stats", which gives letter count, sentence count, word count, etc.
So, out of curiosity, I looked up the books in my favorite series. The first book in the series was 84,000-ish words. The 8th book (we're on 9, actually, but they didn't have stats for that one) was almost 152,000 words. So, not only did he find more to talk about, but as he was more successful, the author's publisher allowed him to produce bigger books.
I don't know what this means, exactly, but I found it interesting.