Thread: Repeated warnings and sys.txt editing.

I seldom post because a search usually reveals what I am looking for but this time I have searched until my head hurts without any luck so I will have to ask.
I have a Chinese car head unit with 10 inch screen running android that arrived with primo installed. I have it working almost as I want with these exceptions. I have enabled TTS using the google engine, street names work OK, my issue is with camera and school zone warnings, I cannot make sense of the sys.txt regarding repeated warnings. The spoken messages come from sys.txt as I can edit them and it reads what I have written.

Before the speedcam cat section I have this:

[warning]
speedcam_enabled=1
is_spoken=1
speedcam_warning=1

warn_distances="120:1000,90:690,70:690,50:690,30:540"
;skin_audio_path="speedcam_lt"
;skin_audio_path="speedcam_ru"
speedcam_continuous_approach_beep_when_tonal=0
;overspeed_min_speech_repeat_delay=-1 ;do not repeat
;overspeed_min_tone_repeat_delay=-1 ;do not repeat

Ignoring the commented out lines some of which point to audio files in Russian and Lithuanian I think?

1: Does the general "warn_distances" override anything written in each speedcam category?

This is my school zone section showing the times disabled temporarily (thanks to previous post) to test:

; S P E E D C A M - C A T : 9
[speedcam_category:9]
;speedcam_snap_distance=50

activated_spoken_type=speech
activated_speech="School Zone Ahead"

;approach_beep_distances=150
;approach_beep_spoken_type=speech
;approach_beep_speech="School Zone Approaching"
;overspeed_spoken_type=none

min_frc=5
use_road_speedlimit=0

;warning_time_intervals_awa="Mo-Fr|7:30-9:00,Mo-Fr|14:30-16:00"

so Question 2: WTF is speedcam_snap_distance
3: Why do I get repeated "school zone" warnings on approach when the approach beep distance etc shouldn't be affecting anything?
4: WTF is "min_frc=5"

Thank you for taking the time to read this and apologies if the answers are given before but I could not find them.

Edit, I have found an example sys.txt on here that has each speedcam category with it's own warning speeds and distances, and also after re-reading other posts I now seem to think that the approach_beep_distance is the distance after the warning that repeat announcements are made.
If I am correct then to prevent repeat speech I need to increase this figure. I had been decreasing it?