Am posting from Bangalore, as am spending the week here. Everytime I've come, immigration has been absolutely painless but I do do my best to get off the plane as quickly as possible. It's a good idea to change some money (cash only, no credit cards accepted) by baggage reclaim so you can tip your car driver. As others have recommended - I'd arrange it in advance with your hotel (Leela, Oberoi, or ITC are all good).

Lounge questions and booking a room the night before already covered by others.

I was OneWorld traitourous and for cost reasons went Emirates from JFK on the A380 this time instead of BA through London. I actually felt really guilty as I arrived at JFK. True story - although not sure if it was to OneWorld, or the miles I would have earned that my wife had already been mentally spending for me. Quite impressed though with Emirates, particularly with chauffeur car at each end, each way. Very convenient. the large screen on board was also pretty cool for movie watching.