That being said, there is a world of difference between moving away from the institution of slavery and having a horrible racist attitude VICE actively promoting slavery as a state economic policy.
I can't quite make sense of this sentence - do you mean versus? It still wasn't true, however, that most northerners even wanted to fight for abolition though, racist or not. Abolitionists were largely extremely radical and not exactly welcomed wholeheartedly by society. As I recall there were a few units that deserted entirely when the war became "officially" about slavery. Still, not a total disagreement there.
More importantly, I think anyone who has done just a bit of in depth reading on President Lincoln would find him to be a very complex man. The fact that Lincoln did not initially make freeing the slaves a condition of ending the rebellion undermines the southern argument that Lincoln and the Republicans were actively plotting a quick end to slavery which was the exigent reasoning for secession in 1860/1.
I think this article is case in point. The fact that he sees ahead that blacks and whites will essentially never get along (as played out in part every time this argument surfaces) and thus supports the only answer he can see to solve it is complex indeed. I think your second point, however, is misguided. To say that is to judge people at the time with the benefit of hindsight. It really doesn't matter what we know/believe to be true now, but instead what people believed at the time. Was there manipulation of the lower "classes" by southern elites? Almost certainly. Does this account for rousing the entire population in support of an institution of which they weren't even formally a part? Not at all.
Basically, as the scholarship stands now, slavery was the equivalent of upward mobility to all Southerners. Despite strong inclinations towards complete independence and self sufficiency, Southerners supported slavery, because the poorest among them kept some hope that they could one day afford slaves (the vast majority of slaveowners had, as I recall, fewer than 10 slaves). This ironically sucked them into a dependent relationship with the economy, because slaves were basically always used to grow cash crops (what good does it do to pay to bring another pair of hands to work on growing food when it's also another mouth to feed?) Anwyay, that's all somewhat complex but I hope the gist of the argument makes sense.
And the undoing of the south was their view of slaves as property - as property, it become war making material and could be seized or destroyed (as in the institution of slavery) where-ever the rebellion was active. Read the Emancipation Proclamation - it clearly states that slaves were only freed in those states in active rebellion, clearly giving the South yet another out had the war ended then.
You make it sound as if that was a direct flaw, though, which it wasn't. Gen. Butler found a way to use an existing law to appropriate slaves, no matter what they were actually being used for. However, the issue of slaves as property is the primary point of friction, insofar as the South's entire economy was based upon it - thousands upon thousands of dollars and a vast part of their labor power. Morality doesn't really even need to enter the argument here.
So why did Southerners get angry when they heard that Lincoln was coming to take the slaves? As mentioned above, everyone kept a little bit of hope to get into that mode of production. But slavery was also an integral part of Southern social structure, and pulling them out of the house of cards would cause chaos(forgive me as I don't recall all the facets of this argument, but again that is the gist of it). Your rocking chair comparison is actually pretty well off the mark. Consider it more as if someone threatened to come in and take away all of the industrial machines in the North. No compensation, just gone. You believe those factory owners wouldn't have been mighty angry? How about the workers? Different regions, different output, but the same basic idea applies.
Also, I would point out that Southerners on the whole fairly well resented interference in their affairs by the north (ie taxes and tariffs that they saw as directly and blatantly harming their exports). They were basically somewhat indignant that the President, who they did not vote for, was haughty enough to reach his long arms down and take what he wanted from them. Davis ended up having to do some of those same things, making him vastly unpopular as the war wore on, but such were the demands and necessities of trying to scrape together a country and armies.
I have no idea where you got your last point at all. An out? Surely you jest. If all the states that had left the Union came back, it's not as if they would have been pardoned and been allowed to keep their slaves. Once the Emancipation Proclamation was released, that was it (and I believe there were a few versions that grew progressively stronger about abolition). Besides, what about all the slaves in regions not formally in rebellion? Lincoln didn't want to make potential supporters angry in border regions. That's a convinient loophole, if you're looking for one.
Even when bringing up the consitutional issues surrounding the creation of the country, the federal system of government and the constiution, the over-riding factor is slavery. From day 1 of drafting the Declaration of Independence it was an issue between the north and south colonial delegates. Subsequent events such as the Mexican-American War, the Compromise of 1850, the Wilmot Proviso, the Fugitive Slave Law, Dredd Scott, etc, all were driven by the base issue of slavery.
All of the legislative hubbub centered more directly on the
expansion of slavery, though. Here again, you could consider that Southerners did not want the federal government impinging on what they saw as their right to take the institution of slavery with them westward. This is why you have events like Bleeding Kansas, not because of slavery itself, but due to the tension over the spread of slavery. Once the Southern populace became convinced that Lincoln meant to strike at slavery
where it already existed did things get really heated. Lincoln tried to avoid that issue as long as he could, but I'm doubtful he convinced many Southerners.
Also, how do you lump the Mexican American War in there?