hi Kitty,
From my memory of being in Darwin in the early 90s, "tropo" was pretty much a reference to going a bit insane from the tropical ("tropo") humidity that builds up towards the end of the dry season prior to the monsoon starting.
"light show"... my only suggestions is that it might be a reference to the thunderstorms that precede, accompany and are everpresent during the monsoon downpours.
As for the other queries, sorry but I'm stumped like you..
Not much helps but hopefully some of our Aussie catters can help out more than me...
Andymac