But one could also define "fill every seat" as "sell every ticket," Part of the point of overbooking seems to be to make this not true. Eg, say a plane has 180 seats. Then "fill every seat" would be filling 180 seats, but "selling every ticket" could mean selling 185 tickets, because overbooking. Airlines would rather sell 185 tickets than 180 tickets, simple.

It's interesting that you chose Azores over Iceland for Ireland to NE USA. For Dublin to New York, it's shorter to go via Reykjavík than Azores. The Great Circle Mapper is great for stuff like this: www.gcmap.com/mapui?P=DUB-JFK%2C+DUB-PDL-JFK%2C+DUB-KEF-JFK&‌​MS=wls

"due to the geometry of the earth" is an interesting way of putting it. "due to Iceland's location" is how I'd have put it. :)

India falls in the first category, not second. You can walk out of the baggage area from the green channel.

As someone who can relate to the OP and their parents, I can say if they are not open to trying "unusual foreign" food, then they really mean it. I don't think a meal or two at a substandard Indian restaurant will convince them otherwise.

No, you don't travel half the globe to eat the same thing you have at home, you travel half the globe for other reasons, like seeing places you are interested in and so on. However, you do have to eat too, it's a basic requirement. Some people aren't comfortable with new kinds of food, and that is ok.

Well, by choosing the fillings appropriately, one can perhaps get something which will be somewhat familiar and not too foreign or strange to an Indian who is uncomfortable with trying unusual foods. But yes I agree that it's stretching it a bit.

Which is why I would never buy a soda in a bar in central Paris, I'd buy it at a supermarket for less than 1 euro. :-)