Got off a few days ago. Most of the camps we stayed at had Yellow Jackets but only a few and none of them were aggressive. One lady on my trip said she got stung, but I'm not sure it was bad and she didn't seem to be in too much pain. They will congregate around meat products and the trash, but as long as you don't bug them too much it won't be a problem.
Not sure on rapid changes since it was my first time down. Black Creek changes often, but was a pretty straight forward run. My trip ran it down the left side, but we saw other groups run the right side with no problem too. The rest of the rapids were pretty straightforward and the descriptions in the guide books were pretty spot on.