Professional Barista question?!

Hi, I work in a Cafe making sandwiches and on occasion I'm required to make Espresso/Cappuccino drinks, I've already gotten microfoaming my milk down, but a little confused on espresso to milk ratios when it come to making a Cappuccino or a Latte. I've tried to ask the other Barista but shes a bit of a "B" about it. So 12, 16, 20 ounce cups, how many espresso shot should each? And do you still foam the milk for a Latte, or is it up to the person? Know that in Italy and Europe the Ratio for a Cappuccino is 1 part Espresso, 1 part Steamed milk, and 1 part foam; but no one really follows that in the US.