Answer to Question 1
The physical environment of the South is somewhat consistent. It is located in the middle of the largest Gulf Coastal plains in the world. You can extend all the way Brownsville, Texas up towards New York, and if you go around the coast, not change elevation more than 500 feet. From a climatic point, it is humid subtropical, relatively mild winters, warm temperatures in the summer, relative humidity being high, and rainfall being very dependable for the most part. These physical characteristics are relatively uniform throughout the area, and this basically leads to a large amount of homogeneity in the South.
Answer to Question 2
Appalachian culture is unique in many ways. These people tended to stay where they were. White, Anglo-Saxon, protestants, that were relatively poor best describes these people. They are isolated from large urban areas and conservative.