I think the main focus here is that this is an Australian musical road comedy about drag queens. They periodically break into song & dance routines that unlike normal "musicals" this is purely lip-syncing along with people like Abba and Diana Ross. In other words, it completely fits and it's realistic. The whole movie is about two drag queens and a trans-gendered person. The crazy thing about it is because this movie is more than 10 years old, Hugo Weaving and Guy Pearce are in it as Drag Queens. Which is really disorienting because I've seen them in other things. Hugo Weaving (aka Elrond or Agent Smith) in Drag is kinda odd. He's fantastic, and I know he had to start somewhere, it's just kinda odd. Guy Pearce should really do more mainstream work. He's done a few big pictures that didn't do so well (The Count of Monte Cristo, and The Time Machine), but Memento was fantastic and has a great following. The movie itself is completely fun and bitchy and real. These 3 "women" have to deal with other people who look down on them and criticize them, and they still are always themselves.
For all the costumes and singing, it's all about being yourself, no matter who that is, and what you look like on the inside.