The Mexican Peso is the local currency although many businesses will accept USD and CAN for an exchange rate.
You may not need a bank account in Mexico. To open an account here, you’ll need a passport and a bill showing your PV address (like your electric bill).
Transferwise is a great app that will allow you to wire funds without paying high wire fees.
Intercam is a recommended bank as they will allow you to deposit your checks in US dollars.
Read more about it here: Best Place to Exchange Money
Google ‘Exchange rate in Mexico’ and it will tell you how many pesos to the dollar. This information changes daily, so the best way to know is to check the internet. Many shops/restaurants will post their own exchange rate, which is usually less than what you’ll find on the internet. To learn the best way to exchange your money here in PV, check out our article: Best Place to Exchange Money