Just reporting back on EPUB checking. I ran tests on both Epubcheck 4.62 inside Sigil and then afterward using Pagina (latest) and both passed without errors. Same with the css (although I can see some issues there myself that need to be fixed). I'm guessing these are based on loose general standards and not severe nitpicking.
Also, thanks DNSB. I think with a few of these posts I should be able to claw my way out of the pit I've dug. Part of the issue...for me, I think...is the fact that I set this up as a print file first with text & paragraph styles and all the font manipulation idiosyncrasies of typesetting taken into consideration. When I began my ebook, I was thinking about how to duplicate that presentation, somehow. I guess the goal is not to do that at all. But how can I give up justify-left to ragged right? It's indecent!