Yes,
there is a duty free as soon as you come down the escalator on the right side.The prices are cheaper than Europe.BlackLabel is popular and is 1 or 5 dollars cheaper.I always buy there as i dont have lug the heavy bottles around in europe on transit.
Yes, Indians tend to "gobble" down drinks.[prestige drinking to get drunk]
Choices are limited but they stock what is most sought by Indians.