I hope below information will be useful for you

1) Try to get original documents attested from foreign office in Australia or Bangladesh & Qatar Embassy in Australia
2) 3 Bed Room unfurnished flat will cost around QAR 7000-1000 and fully furnished will be 10,000 plus
3) Cost of food is around 1,000 - 2,000
4) Mobile / Internet / Mozaic TV packages QAR 1,000
5) Cost of Toyota prado is around QAR 150,000
6) School fee / month iz around 1000-2000
7) Fuel expense around 300 / month