On the first point .... exactly. Calling it Win 9 looks rather like an attempt to reboot the bad PR .... and IF they sort the underlying issues, it'll probably work. It would also account for it being "free", which if it is effectively a service pack, it should be anyway. More slick PR.
On the second point, I'd say that tgat suggests two possibilities. Sone existing users saw the "under the hood" improvements, and decided they justified putting up with the changes. But some of those that decided the "under the hood" changes didn't justify putting up with the UI. That would include me.
And I agree, a user-selectable option of UI probanly woukd have done it. But for me, it goes a bit deeper than start menu. Start menu is necessary for me, but not suffucient. I want to be able to disable MUI entirely, and boot to desktop (yes, I know we can now, before someone tells me) and STAY in desktop mode, 100% of the time, with no context switching. I don't have any interest in Metro apps, whether single screen or multiples.
I just wonder how serioysly MS are prepared to address the dissenter's objections. My suspicion is that it'll be the minimum they can, and be at least 50% PR schmooze. Time will tell, but basing it on past form ....