Thank you cornflake and Fruitbat! In the acknowledgements of a competing book I saw, the author credits her editor and editor's assistant for substantially helping to shape the book. So I thought I might get a little help from my (future) publisher.
Both books can stand alone.
!
Editors help tremendously, and they often do help cut a book to length. This usually means, however, that they may cut in a very brutal fashion when they really want a book, and the writer doesn't do the job. It does not mean you can submit a book that's two or three times as long as it should be, it means that if you're ten or twenty thousand words too long, and the editor loves the books, he may well cut that extra length for you.
But it's never a good idea to go in thinking this will happen. You should have one book, not two, and it should be as well-written, and as close to perfect length as possible. It should contain the
best interviews, and they should be as complete as possible. Cutting an interview for length is tricky, and gets editors and writers in tremendous trouble, when they do it poorly. Most do it poorly. The right way to cut an interview is by cutting an area that's atlk about completely. The wrong way to cut an interview is by snipping away at an specific area in order to make it fit in the allotted space. Writers, and editors, who do this seldom last long.
At any rate, you need one book to wrap a proposal around. There's always some length leeway, but not a lot, so you need to make everything fit within the guidelines a given publisher has. Guidelines are there for a reason, and ignoring them will get you nowhere. You're the writers, and it's your responsibility to cut everything to the point where an editor has the time to help you.
Beta readers? Bah, humbug. If beta readers helped at all, slush would stink worse than a dead fish on a hot summer day. Ninety-none percent of beta readers know less than the writer they're supposedly helping. The one percent of beta readers who could actually help are probably too busy writing to spend time on someone else's manuscript.
And if you actually
need a beta reader, then even a great beta reader probably can't help you.
The best beta reader out there, a thousand times over, is the editor at the publishing house you want to sell to.