What do I need to do to have a valid driver's license in Switzerland? Can I simply use my US one? If I need to have a different one, how can my boyfriend (who is studying abroad in Italy now) also get one?
Switzerland doesn't require an International Driving Permit. You can use your state license.
If you drive in countries other than Switzerland check to see if they require an IDP. Italy requires one as do some others.
the swiss and many others are find with your US license (but have your passport handy too just incase). Your local AAA office can make you an IDP while you wait - and is recommended for countries these day (like Germany - check the list on the ID). Its about the size of a passport and just translates the fields into many languages of what those word mean where you write your name/address/numbers etc. 15$ or so.
The only special requirement for driving in Switzerland is a permit tag to place on the windshield of the car. If you rent the car in Switzerland, the agency should include it. If not renting from a company in Switzerland, ask for the tag or purchase it from the guards at the border.