What would be a good book title/sub-title?
1. Does the term “personal knowledge mastery” make sense to a general audience?
I don't think the term makes sense to a general audience, however I believe it is the right term to use, regardless. The PKM framework invites people to restore (invigorate) responsibility for their personal and professional development. Also, the PKM framework gives a pathway to undo decades of unhealthy systemic mindsets (messages) in the school and work systems. The diagrams used (seek, sense, share) quickly conveys the framework and can get the general audience to start grasping what PKM is about.
2. Is a book on PKM needed now, and if so why?
It is needed now. The working and learning ground is fertile and ready for planting. Selfishly, having your book now will help me immensely as I will use it to help explain and refer PKM to those that I'm working with and growing with.
3. Am I the most suitable person to write this book?
Uniquivately - YES - You will keep it beta centric and keep pushing on the outer edges of learning and working...there is so much to be done...
4. If I wrote this book, would you buy it?
Yes
5. Should I write a book on a different subject, other than PKM? (for example, my ebook covers several topics)
My preference is PKM as your subject. From my perspective, PKM is that lighthouse on your homepage.

I look forward to hearing your decision Harold and good on you for seeking this feedback.