There are more and more things about ePublishing, too much to list them all here, below are just carefully selected.
Pigs, Gourds, and Wikis by Liz Castro
Three Press Blog by Three Press
ePub Validator by IDPF
At last, there are two online course about using MS Word, there are many books and courses about MS Word, but no special for epublishing, these two are closing it.
Word 2007: Formatting Long Documents by Lynda.com
Word 2010: Styles in Depth by Lynda.com