I get my answer to this question through the "The unanimous Declaration of the thirteen united States of America" or popularly known as the Declaration of Indepedence. Its permanent, simple, cut and dry.
"Do different states have different wording or interpretation of their Sovereignty as an individual entity within the union? Where does one find this information?"
Their Constitutions, and most importantly and telling, in the individual ratifications of the U.S. Constitution.
"Had the Unpleasant Situation of 1861-65 not happened, do you think there would have been some clause to hold all of the states or the 10th Amendment would have come anyway?"
I'm not sure I understand this question, the 10th was in the Constitution before the Civil War.
"If the Southern states tried to play out their hand in the courts during the early stages of the CW, would it have led to full blown war anyway? I suspect Martial Law would have been in place early on. But, would that have happened to a Northern state who maybe did not support slavery but also did not support all out war?"
Look to the American Revolution and how it started. Martial Law was imposed and the British attempted to disarm the militias. All hell broke loose.
"In the 1860's it was almost impossible to stay neutral. Could that be said today?"
Sure. The middle sections of the country have common concerns.
"Can we look back at what this Nations Founders set into motion and see it is indeed still that way?"
No it is not, the rights to property has been erased, the rights of basic freedoms are gone.
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David Upton