For those following my intrepid journey to the bookshelves...
I have an editorial letter! I've never had an editorial letter before. It was quite a buzz getting one. Actually I've had the letter for two weeks, but I didn't think to mention it outright until now.
The editorial letter is a standard step of the publishing process, written by your wise editor, and is a list of her (in my case) thoughts on how your book could be improved. I've read of authors who were nonplussed when they saw their letter, but clearly those authors didn't have Kathleen for an editor, because mine was a delight, full of good advice and reassurance.
When a publisher acquires your book, an editor is assigned, as per this happy statement:
Gary Corby's THE EPHIALTES AFFAIR, set in Periclean Athens, to Keith Kahla at Minotaur, with Kathleen Conn editing, in a nice deal, for publication in Fall 2010, by Janet Reid at FinePrint Literary Management (world).
So Kathleen got landed with my ms right at the start and subsequently read the book half a dozen times, thinking about what could be better. She then wrote the letter and I am now acting on it.
You don't have to follow your editor's advice - the contents of the book is ultimately up to the author - but personally, I see that in the same sense as you don't have to have surgery when the doctor says you need a triple bypass.
I'm writing some new bits in addition to cleaning up the ms. One new bit you already know: the historical note I've posted. The other bits are an author note and a character list. They're all things you don't need to worry about writing until your book is sold.
One thing in the sale note that is definitely changing is the title. The Ephialtes Affair was my working title, which I first typed over four years ago, and working titles are usually replaced. What appears on the cover will be something more likely to attract readers. The other thing we don't have yet is a cover. It'll all happen down the road, and as soon as I have a title and cover you'll see it here first.