Santa - Why is the location of Christmas Island significant?

Why is the location of Christmas Island significant?

It is located very close to Indonesia but is Australian territory.
During WWII, Christmas Island was a target for Japanese occupation because of its rich phosphate deposits. Also, Christmas Island is a very isolated place. It has been only lightly disturbed by humans, making its plant and animal life very significant to scientific research. My guess on why it is most important however, is the first reason. I believe i am correct on this information, i studied WWII just last year.
I believe the Meridian of Greenwich, which runs over the U.K. and determines the standard time, continues to run to the other side of the earth and over Christmas Island. This means someone traveling West from the U.S. and leaving let's say on the 28th, will continue to loose time until reaching Christmas Island. It will then become o the 29th. When I traveled from Chicago to China, leaving on the 6th, I had a hard time convincing a lady traveling on the same plain that we arrived in Shanghai on the 7th. She was confused, because the son was shinning all the way during the trip. Shanghai is basically 13 hours ahead of us. While talking on the phone with someone in the U.S., who described the weather as a lousy rainy night, I was looking at the midday son!