Finished the journal article and wrote to the editor again, who said to send it along, so I did.
Read The Art of the Book Proposal: From Focused Idea to Finished Proposal by Eric Maisel. NY: Jeremy P. Tarcher/Penguin, 2004. Then modified the proposals according to its suggestions. Read several other books like this one...they all say the same things.
I'm working on a website for the book; have received many good suggestions for making it better.
Worked again on the list of publishers, moving names between the 2nd & 3rd tiers, in preparation for writing the proposals for the 2nd tier.