Regarding altitude for fuel dumping, ICAO only says that it should not be less than 6000ft, anything else would be a local/company requirement.
ICAO refs also mention the possibility of aircraft going no-coms during dumping (switching off electrics) - how common is that? As a controller, that interests me!
I'd also be interested to hear any words of wisdom regarding the fuel vapour zone and how long it lasts. ICAO is telling us that it needs to be kept clear of other traffic for 15 minutes...
Cheers