Population approx 85k
Currency is the Eastern Caribbean dollar or USD also widely accepted (you might get change in ECD) Cards are widely accepted in the more modern businesses.
Cheat sheet here Antigua Money to work out quickly what things cost to the US and Canadian Dollar and UK Pound.
Banks are in the Airport ( VC Bird )and St Johns and the main shopping centres like Jolly Harbour. Banking hours are Mon - Thurs 8 to 2 fri 8-4 few are open Saturday.
Electricity Voltage is commonly 110 but can also be 220 you may find both british style plugs and us style plugs.
To call from your country the code to use is (268)
Emergency Numbers 911 or 999
Mount St Johns Medical Centre:4620044
Antigua search and rescue: 5621234
Office of Disaster Preparedness (Hurricanes and other):4607076