In the Southern California market, we have two big NPR stations (KPCC and KCRW). Both stations actually produce a lot of their own radio shows, and supplement some nationally syndicated content.

When I visited Oregon, I noticed most of the shows were nationally syndicated, and I suspect that might have to do with how much money they can get from their local regions.

Often true in commercial radio land, but not on NPR. Things are much more loosey-goosey there. Probably because of shoe-string budgets.

No, local affiliates often produce between 20% and 80% of their programming.