I really appreciate the rapid feedback I've received so far.
1) PDF-X has failed for this particular project. I don't know why, but I have tried it on my FW800 1GHz G4, on my 867GHz 12" PowerBook, and on my Core 2 Duo iMac (2GHz, I believe). In each case, conversion to PDF-X failed with an error message (simply saying that it failed) after chugging for a little while.
2) My initial submission of the file was, I believe, a PDF rendering of a PostScript print job, arranged in Preview. This got the file past the Lulu censors, but didn't print properly. (All text printed as gibberish.) Finally, I repurposed the file in PStill, and got a successful print of the book.
Unfortunately, upon ordering eight copies of the book later, one of them was pristine, and the others all had gibberish on certain pages.
I'm working on a more detailed analysis of the various PDF outputs, but family issues are slowing everything down. That said, I wanted to get a reply up here to let you know that your feedback did not drop into a black hole.