What were the two fundamental questions that were resolved by the Civil War?

The fundamental questions responded by Civil war were:

Was slavery to be followed in US

and if states could secede from the union.

Explanation:

The Civil war defined in many ways the face of the country and how it would go on in the future of the country and how the forces of power will shift and how the remaining ones will be able to interact with one another.

The fundamental changes were these:

Slavery was outlawed and it was found that there is no place in America for slavery and that it was unconstitutional.

It was also understood that no state can get away from the Union just because they want to and the union can bring them back if it so deems necessary.