Duty free alcohol cannot even sustain a fire, let alone "start" one. It isn't strong enough. Alcohol is NOT flammable unless it is 100deg proof or over, that being more or less the definition of "proof". Duty free/airport sales is never over 75-80%.
Wrong on both accounts. Standard Whisky, Cognac, Vodka et all are in the region of 80 proof, or 40% and burns fine without being heated. You will find 50% Vodka at many duty free outlets and 60% is not uncommon. Stroh rum is one.
From their home page:
STROH Original is produced in 3 strengths - 40, 60 and 80% ABV.
As for FA's being "Highly Trained Professionals" as safety is concerned.
Per