Here's an interesting forum with tons of informational postings:
BSSD IDITAPROJECT FORUM
The forum was created by the Bering Strait School District in Alaska. They have many mushers as members as well as a few musher's relatives and dog handlers. Several members are extremely knowledgable about the Iditarod and mushing in general.
Look for their "Ask the Musher" segments, where posters can ask literally anything of the top mushers in the business.
Check it out!