Store Hours -- Stores in the City of Hamilton, St. George, and Somerset are generally open Monday to Saturday from 9am to 5:30pm. When large liners are in port, stores sometimes stay open later, and are sometimes open on Sundays.
Finding An Address -- Some Front Street stores post numbers on their buildings; others don't. Sometimes the number posted or used is the "historic" number of the building, which has nothing to do with the modern number. You can always ask for directions, and most Bermudians are willing to help. Outside the City of Hamilton, don't expect to find numbers on buildings at all -- or even street names in some cases.
Sales Tax & Duty -- There's no sales tax in Bermuda, but it's not a duty-free island. Depending on which country you're returning to, you may have to pay duty.
Note: Like various other countries and territories, including several in the Caribbean, Bermuda is covered by the U.S. law regarding "Generalized System of Preferences" status. That means that if at least 35% of an item has been crafted in Bermuda, you can bring it back duty-free, regardless of how much you spent. If you've gone beyond your $800 allotment, make a separate list of goods made in Bermuda. This will make it easier for the customs officials and, ultimately, for you.