Composers from Germany?
There are many composers from the country of Germany. Some of these include Ludwig Abeillem, Jurg Baur, Ludwig van Beethoven, as well as Johann Sebastian Bach.
When and where did Avant-garde music get its start and name 3 leading composers of this era and style?
Well, to be brutally honest, there aren't any famous composers, i.e. any composers that wrote anything well-known, from Australia. None of the composers that have their own category on WikiAnswers are Australian, and there are so many Australian composers I couldn't possibly give you a list of all of them.