TyroPicard:
In answer to your query about min alt for 777 fuel dumping; I can only speak for a UK based employer who have had 777s for 13yrs. For the first 11 or so of these years there was indeed a min alt of 6000' required in the QRH. However, a couple of years ago (something like that) this was removed to come into line with the standard Boeing procedure for 777s.
On a personal view I think it would still be prudent to climb to these sort of levels if possible.