Ingredients
A lot of stores in town carry some specialty Italian ingredients: Cheese 'n' Crackers, Sunsinger, and Art Mart all come to mind. Many ingredients, of course, will be available at most food stores like Schnucks and Meijer (things like lemons, mint, artichokes, almonds, garlic, pecorino, parmigiano, pancetta, etc.). Some of the meats that might be a bit hard to come by at regular stores (beef tongue, tripe) you might do best looking at any of the numerous Mexican food stores around town. You might also try Meat Sciences, which has a little shop with meat that is quite fresh, if cut by students. But in almost every case, if there's a particular item that you can't find, your best bet might be Eataly in Chicago (on Ohio St., just off the Magnificent Mile). Some things would require special ordering from a butcher (pork shoulder with skin on), but you can always ask. Fava beans are often known in the US as broad beans, by the way (sometimes as favas — but you may want to avoid them, since a very small number of people are potentially very allergic to them, usually people with Mediterannean, Pacific Rim or African ancestry. Italians are among that group, however, and eat them all the time). If you're having trouble finding something, ask me and I'll be glad to help out.
Quality
I always insist that there is no such things as "Italian food," but all regions of Italy agree that freshness and quality are more important than price or quantity. If you want a more authentic Roman experience, use better ingredients. Meijer tends to have better produce. If you make bruschette using soft American supermarket bread, it will be pretty horrible — get a nice ciabatta from Pekara instead.
Technique
Al dente does not mean the pasta is crunchy. It means that it's not mush. Generally, American packagers give you a cooking time that is at least 2 minutes too long. Test it regularly: the moment it stops being crunchy, and is firm, it's ready to go into the sauce (generally, pasta is added to the sauce and cooked for another minute on low heat and is then served.
YouTube
There are a million cooking videos. Some of them are actually by Romans; if you've got someone in your group with Italian, check those out and see how the real Romans cook. Otherwise, it's often helpful to watch some other chefs go through it before you try.
Quantity
Do remember that you do not have to make enough for the class (there are almost 50 of us, after all!). Many of these recipes will give very poor results if they are not freshly made, and you actually should never make more than about 500 grams of pasta at a time. (Restaurants do multiple, smaller batches.)
FOOD
EXPLORING ROME