In regards to the last entry (second paragraph, not the first), I got my answer: I have to convert from Simple Tagging tags to WordPress native tags. Manually. The author of Simple Tag[ging/s] hasn’t mentioned an import feature. :( That’ll take a while for me to complete.
[Oct 18@10:47 Woohoo! I stopped being a dumbbell and read in the support forums that there’s an import available IN WordPress for Simple Tagging! Saved myself … a few hours’ worth of work. But I have now discovered that the Category Cloud plug-in cloud doesn’t validate. Ugh. That’ll be sitting on my mind.]