IPhone 4S Wi-Fi Useability in Rio?

I have a Virgin Mobile iPhone 4S
I have plans to Go to Italy and London in January, Rio de Janeiro in February and Sydney in March
3 Months of Straight Travel However,
I understand I will NOT Be able to access my phone minutes or anything overseas; But,
While in these countries, Will I be able to access the Wi-Fi signals at restaurants and places including my hotels and download a Wi-Fi phone app that will enable me to make calls and use data on Wi-Fi

I'm from the United States

Yes, you can use your iPhone to get Wi-Fi signal in Rio de Janeiro and in Brazil in general.
You should download "Skype" on your iPhone and then you can use it to make cheap phone calls all over the world. You need to buy some minutes from Skype before you make the calls though.It'll cost you I think under $ 0.03/minute.