2) What size publisher do I want for my book?
4) Who is their children’s book editor? What is s/he/the house looking for?
5) What does the current book list look like?
The upsides of a big publisher are obvious: they’re well-known, and have established resources and contacts for selling your book. A small publisher can focus more on your book, they take more risks on content, they are independent. I focused on big publishing houses as smaller houses generally do not have the dollars nor the manpower to devote to any one book. Not only could that result in low sales, but also, would discourage them from signing you for book 2! Since 2012 it seems the lion’s share of marketing is on your shoulders either way.
My self-publishing decision was partly based upon this now-outdated fact that I’d have to develop my own marketing plan, execute and sustain it. But there is still a fundamental difference, in that with a big publisher there's still a framework, or formula, a lot of experts in marketing, and that doors are already open to them.
Now, I understand why questions 4 and 5 are important, but I don’t quite get how I as the amateur can determine from an editor’s statement of, “…looking for professionally illustrated storybooks with an expressive voice…” that my book fits that description. OF COURSE I think my book fits!
Also, the advice I got at a conference, that if I chose a publisher that already had a book about a half-millipede, half-unicorn creature whose horn has the magical ability to help others, they probably won't publish a book about a half-centipede, half-dragon whose scales are magical You're bound to feel like you're devoting hours looking through their book lists IN VAIN, as you use the cover image and a 2-sentence description solely to determine whether your book “fits” into the kind of book they publish. My advice, honestly, is don’t waste the time like I did. Start with ten books currently on the market that you like, see who publishes them, then look at the 3-5 most recent books they’ve published, and make a gut decision from there.