So my SSL cert came through (after about 12 hours, instead of the expected 4). I’ve added:
to my wp-config.php, and it seems to be working. I think it’ll be OK to have the whole admin under SSL and not just the login; SSL doesn’t seem to have slowed down the admin interface.
I realized also that I should make sure the WordPress iOS app will connect with SSL. According to the FAQ, it does, though I don’t know if I have any good way of checking that.