For US and Canadian citizens, a visa is not required for stays under 90 days, however they must have at least three months validity remaining beyond their planned date of departure from the Schengen area. Please refer to your country's official resources to determine your visa requirements.
In Milan, we mostly got around by foot or using Ubers. Most of the main attractions are within walking distance from one another. Similarly in Lake Como, we walked around within each town. We used the ferry service to get from town to town. We opted to drive from Milan to Lake Como as this was part of a longer roadtrip we had planned in the region (see the Côte d'Azur itinerary). There are also trains and buses from Milan to the Lake Como region.
While Italian is the official language of Italy, many of the tourist attractions, including restaurants, have staff that can speak English (and sometimes French, German, or Spanish). We did not face any language barriers during our visit. Given that Italy is a European Union country, they use the Euro as their currency. As of September 2020, $1 USD equals 0.84€ EUR (or 1€ equals $1.18). We found that most places accepted credit card, but it is always good to have some cash on hand.
I suggest trying to find accommodations near the center of the lake in towns such as Bellagio, Menaggio, or Varenna. It is most expensive to stay in Bellagio, but might be worth it as it is more lively in the evenings in comparison to the other towns. For example, in Menaggio, things died down significantly as we were finishing up dinner. We found an Airbnb in Bellagio that was reasonably priced and very centrally located. It was nice to see a little bit of nightlife in the evenings.
Often compared to happy hour, aperitivo can be found all over Italy, especially in Milan roughly between 6pm to 9pm. It is a time when friends gather to socialize and relax, enjoy a spritz, and nibble on some pre-dinner snacks (while its not meant to replace dinner, we ended up ordering enough to fill us up that we did not get dinner afterwards).
Aperitivo as we we know it today originated in Piedmont, the capital city of Turin in Italy. In 1786, Antonio Benedetto Carpano started experimenting in his distillery with ingredients including herbs, vanilla, and saffron, eventually creating Vermouth. The drink gained popularity in Turin over the next century. In the early 19th century, Count Camillo Negroni invented the Negroni cocktail made with vermouth, gin, and Campari. This drink also gained popularity in Tuscany and gave birth to the aperitivo culture. Meanwhile in Venice, the spritz was becoming a choice drink among soldiers. Eventually aperitivo became a lifestyle throughout the country and nearly 250 years later, it is still a huge part of the culture.