Fuel is dumped isn't it? Stores are jettisoned.
Myth 2 was written into the fuel dumping checklist on the L1011 and Nimrod.
Having flown through someone else's dumped fuel I can say that we got ITT rise and fuel smell in the cabin. As for dumping while descending in the hold it would depend on your decent rate and the wind conditions as to whether you would encounter your own fuel on the way down.