Accessibility fixes / SR testing

As promised/threatened a while ago, took this through its paces in various combinations of OS/browser/AT and made some tweaks. (and cheekily added myself to the FAQ...feel free to remove the "hat tip" if you're not keen on it ;) )
Separate the first sentence into two—it's a little long. Here's a quick edit and pass on the copy:

> Previously, we used a `<label>` as the wrapper, but this can result in unintended behavior with assistive technologies. For instance, some screen readers will end up reading all `<option>`s contained in the `<select>` as one long label for the form control.