L'Austalie, with more mixed French-indigenous Australian population through intermarriage, a predominantly Roman Catholic country and possibly distinct accent when they speak French...
This is interesting!
I personally believe that the population would be overwhelming European in ancestry, French speaking and Roman Catholic. Although I can see groups of people of mixed aboriginal and European descent living out in the regions beyond the Coastal fringe and Great Dividing Ranges.
Because the aboriginal population is going to take a massive hit from the diseases the European settlers introduce. Although there is going to be less conflict between the European settlers and Aboriginals, compared to what occurred between the French and Native Americans in New France.
In the 17th century? The problem of scurvy hasn't been properly solved yet, so isn't a voyage as long as the one to Australia likely to involve relatively heavy losses? Wouldn't the expectation of this decrease people's willingness to make the trip?
Sorry for quoting this much, however it applies to all points raised. The colony might very start out with a mixed population. Gradually the part of the population with European ancestry will start to dominate, especially after naval technology improves further.