It ultimately depends upon the cost of goods and services. With the market as it is now, I'd say if a family of four can't live comfortably and invest wisely on a maximum job related income of $250,000.00/ yr., then they're living an irresponsible lifestyle which causes grave damage to the economy as well as society as a whole.

That depends entirely on the lifestyle you want to pursue, and what you need to feel comfortable.

Too subjective to answer definitively. Everyone is different, as are their needs/wants.