All but the last 50 or so posts have now been imported into the new system. All the archives have been rebuilt, and all the URLs seem correct. Yay!
I'd had to redo it - it turned out I was missing two dummy posts the first time - but I was able to figure out which ones, and redoing it did not require a full install as I'd feared. I was simply able to delete the MySQL database and recreate it. Annoyingly this meant I also had to redo some settings and replace my custom templates, but I guess that wasn't really too bad. I now know what I'm doing, which makes this whole enterprise much less scary. Of course it still takes time to do.
One of the complicating factors was that I never understood what was going on with the database under the previous set-up. Between cryptic MT 2 documentation and really difficult database administration on the old system (itself hobbled by the fact that certain databases were apparently not available on the machine my account was on...) it was a miracle my blog worked at all. I never understood why it did, but I decided not to worry about it... But the new ISP has a nice web interface for setting up the MySQL database and some instructions for how to do it for MT, so from here on out the upgrades and such should be much easier. And, as a bonus, I now can administer my old comments, which I'd lost control of on my last upgrade due to the database weirdness.
I think the only thing now left to do is throw the DNS switch, although I may let that sit for a bit while I pull myself together... What will happen when I do it (I think) is that eventually when you go to cathygellis.com you will no longer end up here (on the old site). You will end up on the new site and not see the blog. When this happens, because the DNS will have rolled over successfully, I'll have to change some settings in my config files to make it show up (my new installation is currently all pointing to a temporary domain name). I don't think I can do that beforehand though; weird things were happening when I had the new set-up point to cathygellis.com before it actually was on cathygellis.com so I think I'll need to be patient.
Gosh I hope this works...