If there are quiet hours posted then that means no noise should travel off the campsite. If so, first ask to quiet it down. If that doesn't work contact the host or office personnel. No need to act on your own.
We volunteered in public parks a lot and we had to ask many campers to keep it quiet during proper hours. Most complied.
Radios are a big issue. Sometimes you have no idea how far the noise is traveling and it depends on winds, too.
Firepits? If the park's stationary pit is too close to the neighbor there's really nothing that can be done. You can't move the pit to wherever you want. That was an error on the park construction. However, if you know the pit is too close to the neighbor and you know the smoke is blowing his way, common sense would be to be considerate.