More Scrivener and Kindle adventures... I did some research on-line, which suggested the extra carriage returns could be caused by trailing spaces at the end of paragraphs. Luckily, my story is short enough that I could take those out fairly quickly. It means I'm going to have to come up with a search-and-replace strategy.
I dropped in a cover; we'll see how it turns out. I attempted to find a filter for double- and em-dashes, but it looks like they only go one way; so I'm going to have to use search-and-replace there, too. I also put in ❦ as a section separator to see if the floral hearts would come out properly... and...
The preview tool doesn't show my cover. The extra carriage returns are gone (yay!) and the floral hearts code is showing, not the actual symbol ❦.