Thanks, TSN. I see what you mean: Make several single-page PDFs in Photoshop, then combine to single file in Acrobat. I've just tested this, and it works :- ) .......Though I still don't understand why my version of Acrobat - unlike my older version - won't make proper multi-page PDFs from JPEG (per my original question / problem with the "tiny" image on huge sheets.) Oh well.
Happily, and unrelated, I discovered a copy of Photoshop CS on my hard drive. I far prefer it to the Photoshop CS5 that I'd been using for the last few days after my software "upgrade" which led to all these questions. Best regards and with appreciation, Prince Nuada