This is correct - you not only must include the source code for your binary, you also must include it under the same terms as the original source code.
So if someone just happens to distribute the source code for Hancom Office before this is resolved in the courts, would he or she be in the free and clear?
A license can't affect the copyright of any other code. So Hancom is just in violation of the GPL and has lost its right to use Ghostscript; it's not automatically GPL'd.
This is correct. Without a license, Hancom is liable for copyright infringement of the Artifex code if it continues distributing its product. It will be forced to either buy a license or reform its product to use an alternative, but it won't be forced to release its source code.
Probably not. It's unlikely either party will want this to go to trial so it'll probably end in a settlement where the company buys a license on top of damages.
Absolutely you can sell, but your can't restrict user rights