How would a Croatian migrant to Australia have fared prior to the outbreak of WW1? Was there a large Croatian speaking community, did Dalmatians gravitate towards Italians in the community, what was the Anglophone attitude towards Croatians (if any) etc
The short answer is that there was no significant Croatian immigration to Australia prior to WWI.
The majority of Croatian immigration to Australia came post WWII, where they were favoured over other Yugoslavs because they were Catholic. There was then another smaller wave in the mid 1970s.
The 1911 census - http://www.abs.gov.au/AUSSTATS/abs@.nsf/mf/2112.0 - lists 2700 people from Austro-Hungary in Australia out of around 3.6 million people, and just 11 from Servia, 8 from Montenegro, and 16 from undefined European countries.