You may purchase a SIM card for Italy prior to your departure or once you have arrived in Italy.
However it is not possible to use the TIM on-line top-up Service for your sim unless you have an Italian Bank Provided Credit or Debit card.
Alll software is built into the dongle - just plug it into the USB port.
Many cell phone stores represent multiple service providers, and can offer a wide choice of voice, messaging and data packages, as well as often having relatively inexpensive, basic unlocked cell phones (from €29 on up) to which you can add a SIM from any of the cell companies.
Please note: SIM registration is required by the Italian government prior to service activation.
This can be done using your passport when purchasing a SIM card.
They can choose from Travel Sim, One SIM Card, Lemon SIM Card and Clay Telecom.