Choosing a Book Publisher

We've had discussions in the Lounge before about when to decide to write a book (rather than a law review article or something else) and how to choose a book publisher.  In that vein, I recently noted some advice to authors from the Harvard University Press website.  The HUP suggests that:

"Publishing involves a matching process between manuscript and publisher. Virtually all have particular strengths and styles. For both authors and publishers, happiness and long life come when a book is matched with a publisher who has a strong list in the discipline.

So before submitting a book proposal to Harvard University Press (or any other publisher), do some preliminary research. Who published recent books in your field that you especially admire? Which publishers' websites describe books in your area that resemble the one you plan to write? Which publishers seem especially good at reaching the audience(s) you are aiming for? Coming up with a short and focused list of possible publishers will save a lot of time, worry, and postage in the long run."

These suggestions raised a whole new set of questions for me, such as:

1/ Are there really differences between publishers of legal monographs that are as distinct as they may be in some other fields?  In other words, will it really make much of a difference to publication or readership of my book on, say, "Air and Space Law Under the Obama Administration" whether I publish with OUP, NYU Press, Edward Elgar, Penguin Books etc?

2/ If I take HUP's advice and approach a publisher that has already published a lot of books in my area, might they not argue that the area is done to death and suggest I work with someone else?  Of course, that cuts both ways.  If the publisher hasn't already saturated its own market, it may obviously be interested in more works in a similar area to those it has already published, but how do I know this as an author making the proposal?

3/ How is it possible for an author to determine upfront how effective any particular publisher is at marketing works in the author's area, or, for that matter, in any other area?  If I'm using distribution of catalogues, or appearances by publishers at conference exhibition tables, most of the same publishers show up in the legal arena.  If I look at the books I have actually bought and have on my shelves, the standard legal publishers all seem relatively equally represented.

4/ How do I know upfront who is going to give me the smoothest editing process?  Obviously, one can ask around, but even within a publishing house, editors vary from book to book and from time to time (although presumably not as dramatically as changes in law review editors from year to year).

5/ Is it true, as the HUP website suggests, that publishing houses have individual styles at least as pertains to the legal market and subsets thereof?  I have read a lot of OUP's law books lately and I can't say I could encapsulate the "style" of book it tends to publish in any meaningful way.  It is a little easier for me to do so for some other presses, such as NYU Press for works about digital society and law – they seem to market works written by specialists but accessible to general audiences, not too long (usually around 200-300 pages) and not overcrowded with footnotes, but with sufficient sources for an interested reader to follow up on certain points.

Anyone have any recent tips on choosing a book publisher or working with particular publishers?