Rhode Island.
Stewart island is the smallest by far
No. It is an island 16 kilometers (10 miles) east of the Yucatan Peninsula, in Mexico.
There are the un-named, over 100 named island and eight "main" islands.
There are islands in seas and lakes in Australia, and on other non-continent islands as well. One example is Manitoulin Island in Lake Huron, which has several large lakes with islands.(see related...