Back when I took an alcohol education class to be a bartender, it was 1 shot = 5 oz wine = 12 oz beer. The shot size is apparently up for discussion.

I just pour in the mini and mix the drink. Unless I am asked to make it weak, then I use 1/2 a mini. There is a rule against serving more than one drink at a time, as in no doubles, or not serving two beers, etc. Not 2 drinks (coffee and an alcoholic beverage would be fine).