[S3E12] Chuck, Tina, Paul, Angela, Mary and Clark...

Could be wrong, but I don't think Lynch is introducing heaps of new characters 2/3s through the season. We will probably never know who these people are. I think the point is to show snapshots of how other people around town are experiencing weird shit just like the characters we've been following. Just like the honking scene in E11. Strange things aren't just happening to a small subset of people. Strange things are happening all over town. People are disappearing. Twin Peaks is the epicenter of something big that's about to happen and it's effecting everyone.

Edit: this dovetails with that short scene of the dispatcher in E11 who answers call after call after call.