So, I pointed out earlier that iTunes was taking, at best, a long time to import songs. It turns out that restarting iTunes helps when it gets stuck (which has happened a number of times), but despite fairly regular restarts, I still haven't managed to get my full library processed. The best I've gotten (a couple days ago) was 17356 of 21k. And I lost some of those the next two times I restarted.
So, in about seven weeks, still not quite there. Beginning to think I need to ask for my money back.