I have a few questions on headers and sections.
 The guidelines state, "Each section should have a numbered heading that reflects its level in the document hierarchy, as numbered headings allow assistive technologies, regardless of their support for HTML5, to navigate the document structure."
Does this imply that we need to add numbers to headings that normally wouldn't have them, as well as adding headings to sections that normally wouldn't have them?
 The guidelines state, "Only a single heading should be included in a section. If you need to include subheadings, it is best to incorporate them into the main heading."
I'm concerned about the design complications that this could introduce. For example, Chapter 2 of Malcolm Gladwell's "The Tipping Point" begins
The Law of the Few
Connectors, Mavens, and Salesmen.
In our editorial markup system, this is chapter number, chapter title, and chapter subtitle. In our HTML vocabulary, we'd mark this up as
<section class="body-rw Chapter-rw" epub:type="bodymatter chapter">
text of chapter...
(A guiding principle of our markup is that H1 is reserved for the title.)
If we tried to fit all of this in a single block element, we'd get something like
<h1><span class="title-num-rw">Two</span> The Law of the Few <span class="title-sub-rw">Connectors, Mavens, and Salesmen</span></h1>
So in CSS we'd be redefining the spans as blocks, and reading systems that didn't understand display: block on span would render the content incorrectly.
 Is it OK to use h2-h6 as freestanding heads, without additional sectioning elements? A typical chapter might be
section (a chapter)
h1 (the chapter title)
a bunch of text
h2 (primary head)
I've spent too much of my life in Docbook, figuring out where the error was in </section></section></section><section><title/>...