The answer to all of your questions are, it depends.
A cheaper Boxster will not be cheap once you repair it, and one that does not need repairs will not be cheap. Regular maintenance will also be at least 2-3 times that of a 'regular car.' It's a capable daily driver unless you expect to be driving on more than 3-4" of snow (probably not an issue in Turkey). The gas usage will depend on your driving style and distance.
