In general people speak little english. When you need help try asking to younger people, like university students, since older adults are very to understand english. Also when shopping try avoiding small local stores and go to shopping malls, where people are also better prepared. For the public transportation, there is an english version of the mobile app you can download on your phone.
I'd reccomend learning some basic portuguese words just in case.
Feel free to write if you need further help,