You must admit that the North invaded the South. thus the
South was primarily defending their homes.
Sure, in response to an insurrection and acts of war.
The United States didn’t invade anyone. They put down an insurrection.
Most of the insurrection took place on the territory of the United States. Of course the insurection had naval forces and privateers too, and went to other countries. Vermont was invaded from Canada.
No, the south fired on a federal battery and in addition was moving north to threaten Washington. The average soldier bought into the “states rights” lie to shed their blood to defend the right of a few to hold slaves.