I'm back.
Updates installed. OneNote launch via pen button still gives "Runtime Error!", but I don't know if this update was supposed to fix that. Everything else working fine.
Regarding uninstalling Office (Office 365 for me), here's what I did:
1) Control Panel, Uninstall a Program, Office 365
2) Windows Update (only one Definition Update showed up)
3) Restarted my Surface Pro 3, though not prompted to do so.
4) Windows Update (new items showed up), system restarted itself.
5) Office.com to login to my account, re-installed Office 365.
- All my Outlook accounts came back perfectly synced.
- All my other Office apps (PowerPoint, Excel, etc.) asked if it okay to set those as the default programs for the file types, but even the "Recent Files" lists showed the proper history, etc.
- Folder references for my Office files all came back automatically.
Took about 30 minutes round-trip.
As the doctor is known to say, "This won't hurt much. You'll just feel a little pressure."