Well this was very much a chore, but I have success!
I was provided the Microsoft Access database file on a DVD by the previous webmaster company, and using a Microsoft Access software (same name as database file type), was able to export each of the database tables as a CSV. I then opened each of the dozen or so CSVs in Microsoft Excel, merge them one by one according to a shared field, until I have one huge XLS workbook spreadsheet. Each CSV from the original database shared at least one common field in a linear chain, so this was possible.
It took much formatting of the data to eliminate non-ASCII characters and make sure fields properly open and close (because commas and quotation marks upset the CSV). Also each article post was broken into several database rows in the original document, so there was much merging of rows involved there. Also, every article post has images throughout, and I needed a way to let these flow with the body text of the articles, and so I inserted HTML tags to create image and caption divs.
Then I had to make columns conform to new WordPress database, and give meaningful names to those extra columns that still had useful data but did not conform to the Kobozev's CSV Importer plugin.
Finally once my XLS workbook spreadsheet was ready with nearly 3000 articles, I export in small batches to CSVs, and upload with Kobozev's CSV Importer plugin.
Thank you to Kobozev's CSV Importer plugin, and to all who make WordPress so grand!