If you Google most pc games, you'll generally find pages and pages of "buggiest game in the world" testimonials. Unlike consoles, every PC is built a bit differently, from hardware to drivers to installed software that all interact in unpredictable ways, So a majority may have no/little problems and thus be silent, while those that do, tend to be vocal. Which isn't to say games don't have fairly universal bugs sometimes, as well. They do.
Most of the common bugs and little glitches in Kotor2 that I'm aware of aren't game-stoppers - and you may not experience any of them. No one can really say.
The Official patches are the one you mentioned at lucasarts, and it's related Media Patch, which just improves the music and movies; nothing to do with gameplay. If it's not authored/approved by lucasarts, it's not Official, and it's player created.