Australia
The official language of Australia is English so you would say "Merry Christmas"
They brought Christianity.
In Australia, Christmas Day is called Christmas Day, just as it is in other English-speaking countries around the world. It is preceded by Christmas Eve.
It is uncertain what the question is asking. Australia simply calls Christmas "Christmas", and pronounces it the same way it is pronounced in other English-speaking countries.
"Merry Christmas, mate!" English is the predominant language in Australia, so you say it in exactly the same way except with the addition of an Australian accent. Or: Usually you just say "Merry Christmas" or "Happy Christmas". In the vernacular, you might say, " 'Ave a good one, mate."
A silver coin.
They brought Christmas and cultural dances.
Yes. The English created the first official white settlement in Australia, and they brought their traditions and culture with them, including the drinking of tea.
Christmas is called Christmas in Australia.
That's up to the gift giver. There are no set rules.
The English settlers of Australia brought with them many simple, traditional English foods. These include potato dumplings, jam pudding, roasts and stews, lamingtons, and kidney pies.