This can be called the coastal zone or littoral zone.
(the terms coastline and seashore are each one word)
ocean
The usual term for a coral island is an atoll. Some exist in otherwise deep ocean waters.
At the coast. This is the term for where land meets the sea.
The correct term for places where oceans meet land is coastlines or shores.
land-locked
It is the Pacific.
The term "land conversion" is converting a forested area to another use such as agricultural land or urban area.
Yes. The term bight can also refer to the gently inward curving coastline that contains the water.
The Artic Ocean.
a large ocean inlet, or a narrow ocean channel between two bodies of land
That depends on whether the land is surrounded by water or something else. If it is surrounded by water, it is an island. If it is surrounded by water but is sufficiently large, it may be called an island continent (an example is Australia). If it is a land area completely surrounded by high mountains, rivers will flow to the land that is surrounded instead of to the ocean in that area. That would make the land an endorrheic basin.
The desert is the term for a large land area that receives little rain. Almost every continent has a desert except for Antarctica.