Southern leaders were concerned because cotton was the only major crop that was being grown. If a disease, natural catastrophe, etc. destroyed the cotton, the South had no other crops to maintain their economy. They relied solely on cotton.
It was the people who were in charge of electing officials who technically controlled the elected assemblies in southern colonies, since these were the people whose interests the delegates were looking out for.
A bay is a body of water that connects to another body of water however a bay can be surrounded by land where as an island is a piece of land fully surrounded by water on all sides