Forgot about comment above, here is 100% solution
of 2. issue with save all designed things:
- siren sound sets (CfgVehicles) needs move from soundSetsInt[]={}; and soundSetsExt[]={}; to the soundSets[]={};
- for each siren sound shader (CfgSoundShaders), in volume parameter, to the value need add a camPos, for interior one: (1-camPos), for exterior camPos
Check this .cpp file with done of example work to fix issue https://pastebin.com/navpYGWb