Update: After a brief exchange with the very helpful Kevin (also a poet) from Smashwords, I exercised the ‘nuclear option’—i.e., I saved my Word document as a plain text file, then re-applied all the formatting from scratch. It worked, so everything now looks the way it should. (As a precaution, I re-saved and uploaded the updated document to Amazon as well, so that the files will be consistent with each other.)
On the title thing, I chose to capitalize the only the first word. My updated file is now being reviewed, so I should know soon whether or not I have to do anything else.
(8 February 2017)