MacOS – All fingerprints erased

Although you don’t mention the right MBP model you have (year/model/etc.) I’ve had similar issues that were caused by the graphic card being faulty. This started to happen “one day” and then it happened more and more often, but in random places, which made it hard for me to find out what it was. I ended up in an Apple Store and they had to replace the board (which was still under warranty).

I’d say you take it to an Apple Store for inspection.

What could have caused this? What does that error even mean?

You may have a hard drive that is going bad. The flashing folder means that the Mac can not find or read the needed system files to boot up.

What is the current status of my computer? Is everything wiped from my HDD?

Hard to say, but probably not. You could remove your harddrive, put it in an external HD dock, and try to recover you personal files. Or, you could restart it while holding down the "T" key to put it in target disk mode and then connect it to another running Mac computer via a Firewire or Thunderbolt cable. Your hard drive will show up as another disk on that computer and the can get to your files.

Either way, I would consider replacing the hard drive. To check for errors, in the Terminal (/Applications/Utilities), type

grep -i "i/o error" /var/log/system.log

If you see any results, your hard drive may be dying.

3. Is is safe to leave it sleeping on the Disc Utility until I get home?

Yes

4. Can I restore from Time Machine if I didn't backup system settings?

Yes