When you are eating out, you will be given bottled water, asking for tap water is frowned on. You will be given a choice of sparkling or still water. If you really don’t want to pay for the water, which actually is rarely expensive, you are better of drinking from one of the many street water fountains, rather than ask for a glass of tap water. Tap water in Italy is safe to drink, but you will find it isn’t often cold and it can often be cloudy due to the flouride etc in it.
Drinking coffee. You see lots of people say Italians don’t drink a cappuccino after 11, that’s true, but it’s not frowned on, you can ask for one. So don’t worry, if you want one, ask. The reason Italians don’t drink it, is because the light taste and the milk they think goes well with breakfast, so to them it’s a breakfast drink, rather than a drink to have during the day. When you get an expresso, you will be given a cup of water normally, the water is a palette cleanser, not to cool down your coffee.
Bread in restaurants, often you will be given bread, in some places it will come with olive oil or maybe an olive oil and vinegar mixture. Other places it won’t. If it doesn’t come with it, don’t ask, it’s not meant to. The bread isn’t for you to eat before your meal, its actually to eat with your meal. You will often see Italians use it to soak up the sauces and clean the plate, how you eat it is up to you, but don’t eat it on it’s own.
Don’t ask for Parmesan for your pizza. If the pizza is meant to have it, it will come with it. Pizzerias plan their menus carefully, it’s rare you get a make your own pizza in Italy. Pizzas that come without mozeralla that suit mozeralla you may be asked if you want it, that’s a choice you can make.