Yes.

This content is hidden both visually and aurally, and doesn't appear in the keychain until the button is activated (expanded = true).

Apparently yes.

This content is available by default until the button deactivates it (expanded = false) which removes it visually, aurally and from the keychain.

Add the attribute data-pab-expand to the dt to open it by default.

Yes.

Any question may be expanded on page load by referencing its id in the URL.

For example this content could be automatically opened by adding "#faq_3" to the URL in the address bar like so:
https://codepen.io/2kool2/pen/ZOkojB#faq_3

The focus caret is moved to the activation button when referenced in this manner.

Yes, though it only opens on first click. After which it simply scrolls the question to the top of the viewport.

Add an unique id value to the question dt then reference the id in the anchors href.

Yes.

The height of a hidden block is calculated when the activaton button is pressed. It's also recalculated when the browser window is resized.

In fact this module should easily scale to 300%, limited only by the display width and word length.