1) While Waze does not track Traffic Lights, Waze does know the "time to turn" (or go straight) at each intersection. This, like the speed data for the segment, is kept in 10-15 minute chunks for the entire day. Waze takes the "time to turn" into account when routing.
2) The popup that comes up while driving for Police (or Hazard, etc) does contain "Not There" and "Thanks". Be aware that this pop-up only happens when one is travelling in the direction the report was created for (so if you are travelling north & the officer was reported by someone travelling south and they didn't use the "other side" option, you won't get the report). Please note, the "other side" option does not work for divided roads (like the Interstate Highways in the US).