I will answer what I know.
1. Put 3d or any other map img to ../Garmin/Map/
2. Yes ../Garmin/.system/JCV/
3. Jcv from map release specific for StreetPilot.
4. Traffic don't work on Streetpilot Android
5. Put them in ../Garmin/POI/ Not all pois work so must use ones that do. I hope someone with more experience with Speedcamera POI will share their experience.