Well, here's the answer you keep asking for. It is clear that Lincoln was a racist who didn't believe in slavery. There are many reasons for the abolishment of slavery but I believe kindness was not one of them. The "Black" code laws passed by some northern states to keep the negros out, made clear the attitude of northerners. Northerners disliked negros just as much after the war, as before. In my view the reasons for abolition were af follows, in order of importance;
1. ECONOMIC - Freeing the slaves would have little impact on the economy of the north. It would insure that the south's economy would remain static for the forseeable future. This would insure that the southern states could not rise to become powerful enough to again treaten the authority of the U.S. Goverment. There was a very real fear of this, especially among the union veterans.
2. VOTING BLOC - The newly freed slaves would become voters, Republican voters for the most part. This would maintain the then present power structure, which appears to be so important to politicans.
3. VINDICTIVENESS - After the war the abolitionist were very vindictive towards southerners and the amendment would reinforce the power they held over the people of the south. Lincoln's forgiving reconstruction would be replaced with a very harsh policy, with military occupation.
4. POTENTIAL VIOLENCE - Many slaves were promised freedom for their part in winning the war. To go back on this would invite much unrest and could possibly require further military intervention. The world community would look in distain towards the U.S. Goverment if it reneged on the slavery issue, and feel it couldn't be trusted.
Your #3 seems to argue that it was the post-assassination congress the passed the 13th Amendment, when it was actually passed in by the Senate in April of '64 and by the House in January '65, then sent to the states. With the house stalling, Lincoln even had it put onto the Republican party platform for the November '64 elections.
You're also, I think, neglecting the fact that, even though most northerners didn't like blacks and didn't particularly want them living among them, they detested slavery and blamed it for causing the war. Look at the popular songs of the north. The Battle Hymm of the Republic isn't about installing higher tariffs. While the reasons the north went to war against the south at the beginning are complex and include economic factors, the fact is that it became a crusade, and there was no way that the north was going to allow the factor that they blamed the war on to continue.
As I said in an earlier post, mostly I blame the war on politicians on both sides who demagogued the issue for 40 years before the war, hardening battle lines and increasing sectionalism.