I didn't see anything in the docs that touches on those subjects in detail (I did skim the docs looking for sections and pages that might contain answers to my questions before I posted), but please point me to the page that does if you know of one and I'd be interested to read it! I trust that your perceptions and information are accurate, but cite-able and reference-able information is also valuable.
"For the most part Pub/Sub delivers each message once, and in the order in which it was published. However, once-only and in-order delivery are not guaranteed: it may happen that a message is delivered more than once, and out of order."
