The other thing that's changed is that if you want to blog about cooking, you need to become an excellent photographer, not just a good writer. Readers want to see the food. They have high standards because they're accustomed to beauty shots in magazines. Drummond is famous for using dozens of shots in a single post.
To your second question, there was so much more to say after five years. In addition to 17,000+ words on food blogging, I updated the chapter on freelance writing (harder than ever) and enlarged the section on self-published books (easier than ever). I added more details on cookbook writing and production, because I co-wrote one ("Grilled Pizzas & Piadinas") with a chef after the first edition came out in 2005. I wanted tell readers more about what to expect.
In a few more years, I hope to write a third edition to explain writing apps for mobile devices. That was just starting when I turned in this version.
Q: In your chapter on being a successful freelance writer, you say that "you might have to write for free when you're starting out." Did you agonize over giving that advice?
A: Oh gosh yes. I would like beginning writers to get paid. But that's not how the system works these days for smaller publications, and they are the easiest ones to get into. I don't advise doing it for long, however. I tell people to do an excellent job, get a clip and make it clear they'll ask for money the next time. If the editor says no, try another publication.