What herbs and spices are in "Italian Seasoning"?
I cannot +1 Peter V because of my poor reputation, but he is right: in Italian cooking you don't go for mix, what you look for is a balance between a few ingredients, normally one from different kind of foods: one cereal, one vegetable, one spice for example.

The main spice (or fresh herb) is parsley: it is so common that it is used in figurative language as well, think about a celebrity you see everywhere, just like parsley.

Fresh basil is a must for spaghetti sauce and freshness, as Peter V said, is the only option.

I never heard about red pepper in Italian cooking; I bought mine during a travel in Asia and use it for Asian food. Black pepper is for sauces and meat, white pepper for fish, normally.

Oregano, thyme, marjoram, are common, and they normally don't mix. Oregano is widely used on the top of some pizzas, especially when they have got anchovies, capers and/or olives on top.

Pizza margherita requires fresh basil.

Rosemary, bay leaf and sage are used commonly with meat or beans/lentils: in this case you often prepare a bouquet tying together some small branches from these three herbs with a cooking lace and let the bouquet rest in your preparation for some time.

You should probably add fennel seeds to the most-common-Italian-spices list.