Do I need a passport to get to Puerto Rico from the US?

No, if you're traveling from the U.S., you do not need a passport to visit Puerto Rico. As a U.S. territory, Puerto Rico is a domestic destination, so you can travel there just like any other U.S. state.
Is English widely spoken in Puerto Rico?

Yes, especially in the metropolitan area around San Juan. However it's not uncommon to come across people of any age, who are uncomfortable or not confident in English. It's good practice to great people first in Spanish (Hola, Buenos Días/Tardes).