Capn Rex.
The main reason the A380 financials look so good for EK is due to the low average purchase price and in service operating cost guarantees.
As far as fuel is concerned I would expect EK to effectively pay less than QF due to their purchasing power. I am told the US military have the best 'deal' followed by the Star Alliance group. The invoiced cost is not the end cost due to volume discounts and rebates etc.
I am currently paying 12.262 cents per litre less than the 'pump' price for my fuel from Shell.