This was a popular song a couple years ago Azonto , there is even a video of a bus driver dancing to this song whilst driving. Most likely they were listening to the radio this website will let you listen to radio from fiji http://streema.com/radios/country/Fiji .
Joining any Fijian association will just mean you fork out money for them for their kava sessions. If you really want to know the history all the way prior to European settlement to the 1990s period, read the book "Fiji in the Pacific: A History and Geography of Fiji" . You can find it here. This book is used in Fijian schools. You will learn all the history except language.
Check out Talanoa with Dr T on Facebook. Resources are basically non existent so the next best thing would be having an actual Fijian talk to you, listening to Fijian radio and TV programs
There really isn't a definitive best book in Fiji. The only literature we did from Fiji in school were short stories. I thought Subramani was pretty good so try this:
https://www.amazon.com/Fantasy-Eaters-Stories-Fiji/dp/0894106317