(yes, some of this matches iain's writeup, I'm not stealing from him, just using sources that say some similar things... I'm including what he's written for completeness)
The first documented foods that look similar to what we call pizza was a dish eaten by early Greeks and Etruscans, called plakuntos. It was a flat, round bread, baked with herbs and the occasional onion and garlic. The Romans later borrowed the dish, and it is mentioned in various historical records. By 1000 CE, a dough disk with herbs called picea was common in Naples and other parts of Italy. It was used mostly for the women to satisfy their hunger while waiting for all of their bread to bake in the communal ovens in the towns.
For the longest time pizza was sold by open-air vendors, or at small stands. Port'Alba, however, changed all that, as the first of what could be called true pizzerias. Lava rock from Mount Vesuvius was used to light the wood-fired ovens, in an innovation of how pizza was cooked. By this time, the tomato had been discovered in the new world, and found to be rather tasty.
Cheese was first added to pizza in 1889. Baker Raffaele Esposito was issued a royal summons, required to prepare a pizza for her majesty, Queen Margherita. He took two common ingredients, red tomato and green basil, and added white to represent the colors of the flag - to do this, he used mozzarella cheese. It went over well, very well.
In 1905, Gennaro Lombardi opened the first pizzeria in America, in New York City. However, pizza was not a huge hit in America at first, remaining mainly in Italian neighborhoods. American soldiers got a taste for this dish when over in Europe for World War II, and upon their return, introduced it to their families and friends, and demand skyrocketed.
Tomato sauce was not used on the pizza until after the first pizzerias in New York City were set up. The stronger-flavored Roma Tomato (plum tomato) was hard to come by, so spiced tomato sauce was tried. The resulting pizza became the standard pizza of America, with regional variations.
Since then, pizza has become the number one dish in America. Pizzerias now outnumber hamburger places in most of the country. The largest chain, Pizza Hut, has over 4,500 restaurants.
Oh yes. Pizza means "pie" in Italian. So saying "pizza pie" is redundant.
How to cook your pizza depends on a lot on the crust. It also has just as much impact on how well the pizza turns out. Pizzerias have specialty ovens dedicated to cooking pizzas and similar foods. You can't get the same ovens, but you can turn yours into something very, very close.
First, you need a pizza stone/baking stone, or something similarly effective, such as unglazed tiles, ceramic I believe. These provide proper heat to the bottom of the pizza. A cookie sheet, or a plain pizza pan directly on the rack will not properly cook the bottom.
Now, preheat your oven to 500 degrees for a full hour. An hour? Yes, this amount of time is necessary to make sure the stone is completely and evenly heated. Warning - 500 degrees is HOT, and you will be greeted by a serious blast of heat when opening the oven, so be careful. The higher temperature will cook the crust more thoroughly, making it firmer and crisper, instead of the softer texture that it will have at lower temperatures.
You can either cook the pizza directly on the stone/tiles, or on a pizza pan/pizza screen. Cooking it directly on the stone offers the best and most even cooking, but can be difficult to do depending on both the size of the stone you're using, and your agility with a pizza peel. Cooking the pizza on a screen offers good results, and makes it much easier to put the pizza in the oven, and remove it later.
As far as cooking time, it should be about 10-12 minutes. Watch the toppings and the color of the crust. This should help you judge the exact amount of time.
Sun-Dried Tomato, Garlic, and Pecorino Pizza
1 8 oz. jar sun-dried tomatoes in oil
4-6 cloves garlic (roasted garlic also works for a sweeter taste)
8-16 oz. shredded Mozzarella cheese (depending on taste)
1 C. shredded/grated Pecorino Romano cheese
After getting the pizza crust flattened and ready, brush the crust with a good coating of oil from the sun-dried tomatoes. Then, add the sun-dried tomatoes, as few or as many as you want - you want them below the cheese to make sure they don't char. Sprinkle about half of the minced garlic on now also.
Put half of the mozzarella on the pizza. Add the rest of the garlic. Then sprinkle the rest of the mozzarella, and the pecorino, on top of the pizza, sprinking them on at the same time to mix them well.
"Pizza", by James McNair
"The History of Pizza", http://www.ghg.net/coyej/history.htm