Yes. States, where the institution of Slavery was legal to practice, had a legal right to defend the institution if it had a slave code to govern the practice.
Yes. Slavery was tied to State representation in the US House of Representatives through Article 1, Section 2, Clause 3 of the compact entitled “The Constitution of the United States”. Remove slavery and States lose representation and therefore the power to affect legislation.
No. Article 1, Section 2, Clause 3 are delegated powers from the States invested in its agent, the Congress of the Confederate States, according to Article 1, Section 1 of the Confederate Compact.