Some of the items are downright silly: anecdotal items strung together to make a case, not a serious consideration of significant facts. Douglass would make much of rumors of Black Confederates to get concessions from the Union government. Northerners would credit all manner of rumors of what was going on in the South, and may not always have distinguished troops from laborers.
Davis's last ditch feelers to gain foreign recognition shouldn't be valued more than they deserve. There was still enough support for slavery to frustrate such plans up to the last desperate weeks of the war.
It's not hard to believe that some slaves stood by their masters. But such loyalty didn't add up to what the author wants to make out of it: a vote of confidence in the Confederacy.
Wages of free black workers at one defense plant say little about the overall condition of Blacks in the Confederacy. Black Union troops, contrary to this article, did eventually receive pay equality with White troops. We have only the author's word that the same was true of Black workers with the Confederate army, and it's doubtful that he'd make the same claim about slaves under army control.
Sir Moses Ezekiel does sound like an interesting character. It's worth noting, though, that segregationist Woodrow Wilson dedicated the monument. "Black Confederates" -- real or imagined -- don't add up to racial equality or integration, as we understand such ideas.
Davis's last ditch feelers, if true, were meaningless since constitutionally Davis lacked the authority to end slavery. Neither he nor the confederate congress could make any law whatsoever affecting slave ownership. His promises, if made, were empty and were only a ruse.