Can't import Contacts from abbu, errors in Notifications, FaceTime
Unfortunately, once Yosemite was installed, even Finder wouldn't open. I had to travel to the nearest Apple Store where even the Mac Genius was pretty stumped. His best guess was the build of Mavericks was corrupt on the new laptop to begin with, or the build number was invalid for some reason. It's not clear why that didn't fix itself when Yosemite was installed.

In short, the only solution was to do a full backup, completely wipe the system (completely - there was no data on the SSD at that point), reinstall Mavericks, upgrade to Yosemite, then copy the files from the backup without restoring any settings or preferences, and then set up each program individually from scratch.