I want to ask: What happens in the event of a hard disk failure or a Windows reinstallation?
Do I have to go through the entire process of re-downloading and re-verifying the entire blockchain every time?
The same thing happens as with all your other software installed on that disk. You will have to re-install and re-download them when your operating system or the new hard drive is up and running.
Or is there a way to download a pre-verified blockchain and just continue from whereever it left off?
Where would that downloaded "pre-verified" blockchain come from? You still have to download it and let it sync with your Bitcoin Core. Why would you opt to download it from an unofficial source instead of using the official one? I understand that a second download and re-sync is a pain in the ass, but using someone else's data makes you potentially vulnerable to any modifications or malware that person could have intentionally put there.