After reinstalling BG2 and the Throne of Bhaal expansion, I was set to waste good amounts of my time (again). However, I noticed that 80% of NPCs wouldn't speak to me whatsoever! It would say something like "So-and-so has nothing to say to you.", or something similar. It was impossible to advance because even Gaelen Bale (sp?) wouldn't even talk! Is there a patch for this? Is it Throne of Bhaal screwing up my BG2 files? Or is my antisocial behavior being transferred to the wonderful world of Baldur's Gate II?

By the way, I've tried reloading, leaving the area and reloading, resting, leaving, then reloading, dozens of times, to no avail. Sigh.

Yep, official ToB patch fixes this common problem. You can get it from here:
http://www.sorcerers.net/Games/BG2/index_misc.htm

Since you have ToB installed you should be posting in the ToB forum. Please go read the forum descriptions. Moving to the ToB forum.