One great way to promote your ideas is to turn one or two chapters into a 60- or 90-minute talk and present it at professional associations or conferences. Local chapters of professional associations are typically starved for good presenters.
Similar: Post a few short podcasts or (better) videos in which you hit the highlights. Take a look at some of Peter Block's videos:
In addition to posting on blogs as a guest host, create a blog for the book and post to that. You might also create a forum where people can discuss the ideas (though this is risky if there's not enough buzz yet).
If your highest priority is feedback, you might post an offer: "I'll send you a free chapter if you'll give me feedback." Then people can tell you which chapter they want, and give you their email address. Asking people to make this small commitment (even if they never give the feedback) can increase their interest in it.
Find online forums where your ideas are relevant, and help people there. I don't know whether it's a good idea to post about your book there. Anything that seems like an advertisement can turn off as many people as it attracts. But your signature can mention your book and a link to the book's web site. If you're helping people, they'll want more.
Whenever you have new content (chapter, blog post, video) post the link to Twitter and Facebook. It's also a good idea to post your thoughts there, so that your stream is more about offering ideas than advertising.
If we distribute initial chapters to existing clients, do we actively solicit feedback and potentially change the direction of the book?
Yes, but only if you're open to the idea of changing the direction of the book... which, of course, you are. ;-)
If we post on blogs as a guest host, to what degree to we integrate comments and questions from visitors?
To the degree that their comments and questions fit your intentions. Of course, the comments and questions may shift your intentions. You're the expert on what you're trying to say. Readers are the experts on how they react to your words. So keep listening, keep probing your intentions, and trust yourself.
One of my mentors, Jerry Weinberg, often includes ideas from reviewers and other contributors. If the contribution is a sentence, Jerry quotes the contributor inline, within a paragraph of his own. For a longer contribution (usually a paragraph, but sometimes two or three), he uses a block quote. And in either case, he names the contributor.
In many of Jerry's books, each chapter ends with exercises or ideas for further study. Many of those come from reviewers' questions.
If you're going to quote reviewers' comments, it's probably a good idea to let them know that before soliciting their feedback. Depending on the length of your quotations, it's probably a good idea to ask whether its okay to use their words. If people take the time to read your chapters and give feedback, make sure to list them in your acknowledgments, whether you used their comments or not.