Question about family support for PhD students

Im considering a PhD position in Vienna, and I was wondering if anyone here is currently studying in Austria.

I have a family, wife and a daughter and I was told the government gives some support for families, does anyone know what is this support?

Does anyone know how much are the taxes for phd students? I have been told something around 25%, but they are not certain. Is it possible to get any tax benefits due to having children?

How is life in vienna for international students? How hard was it to find an apartment? can you recommend a good website to search?

TIA!