Most students use the on campus branch of RBTT. They are usually open 8-2p (as most bank hours are). Another popular bank option is Scotia Bank. Choosing between the two comes down to use of ATMs and associated fees. These fees change all the time so it’s probably best to look it up on their respective sites.
To open an account, you’ll need a US ID (passport) and a letter of good standing from your bank at home.
I had an account open through RBTT to pay for rent while living on the island and a safer storage of money. I brought money to the island via traveler’s check’s which held a little more value than actual cash.
Here are the conversion rates from Nov 2015 for reference.