I get 380-400kms from a tank around town, and about 450 or more out on the highway, but I have not used a full tank on a highway trip yet so can't give an acurate answer.
Not a chance in hell I'm driving on a dirt road at more than 5km/h
In the rain....woooooo....Very slippery!!!! might need different tyres but it doesn't rain much.
My opinion is get a cheap GTS (No turbo) to learn in then upgrade later. Not so bad if you ding a pole or something. This can also give you more of an appreciation of the turbo power instead of just taking it for granted and being sadly disappointed when you drive something else.
Don't forget the more you pay for the initial cost of the car,,the more it will cost to maintain..(as a general rule to allow for budget.)