Depends on what you were drinking. If you sticked to one type of alcohol then the smell wont last long. But if you had different types like beer , vodka , whiskey , gin .. All in the same night , then the breath might stay with you even when you wake up in the morning
Not too long if you go brush your teeth.
Brush your teeth, drink some water.
Depends on how many. If you are asking for purposes of a breathalyzer the human liver processes 1 oz of alcohol an hour