I've always wondered what happens to Twain in a world where the Confederacy won. Which way does he go?
He was born in Missouri, raised in Hannibal and settled as an adult in Elmyra, New York. With books like Connecticut Yankee... and Prince and the Pauper, as well as his fondness for travel, I'd say he'd stay with the Union. It was the war that caused him to end his riverboat career. We have some disdain for the racist language in Huckelberry Finn. We should also see a story about a boy with an alcoholic father, who turns to an escaped slave and Native American as adult mentors.

On the question of borders, I might suggest that the Confederacy get (what is now) the Interstate 8 corridor from Arizona to San Diego. That would be in exchange for an enlarged West Virginia.
The Irish in the South, 1815-1877 | David T. Gleeson | University of North Carolina Press
The Irish have been in the South longer than the north since the 1600s in Virginia and Maryland. Irish emigrated at a 72% rate in the southern colonies during colonial times. The South will have trouble attracting the Irish immigrants, but for the southern government to pay for the ship and food would be a good way to attract the immigrants

In reply to immigrants, the Germans are the least likely to come to the confederacy as they were anti-slavery and pro-Union. During the Civil War, they were the backbone of Missouri’s union forces during the early section. The wasp backlash during the 1900s party was hard to do with not just a lost cause movement but a significant forced reconstruction period. I don’t think the South will give up slavery easily, and if it is to give it up, it Has to be at a slow, very gradual pace given the pro-slavery government.
The question isn't as much about the Confederate elites' willingness to entice immigrants to come as much as it is about the economic opportunities those immigrants would have in Confederate society. The Civil War was an extremely damaging time for working-class whites in the Confederacy, who were subjected to the draft like their Northern counterparts and even to "food impressment" if they had farms—because the Confederacy was unable to grow enough food to support itself during the war. While a scenario in which they win might have some of these factors reduced, it's still indicative of the attitude the planter elite had towards the lower classes as being one step removed from their slaves.
While you point out southern racism, it was an American phenomenon as both sections were intensely racist. Before the Civil War, Black people attempted to conjugate up north northern legislation made sure to do something about it, name the fugitive slave law and state laws banning Black people from coming. Anti-Catholic bigotry lies mainly with The Yankee nativists protestants, particularly in New England. Nativists also helped found by the old 19th century Whig Republican Party.
I don't know what this is a response to, because I did actually point out that the postwar Union would have plenty of people who would condemn both the planters and their slaves and dismiss the idea of abolitionism.
We agree upon the south cajoling to immigrants, and I agree with other aspects in the assessment. The South could never be an industrial powerhouse like the north was. If indeed a southern industrial revolution will happen gradually in the South will be able to enjoy the fruits of its industrialization. But for the most part, the South would be rural, and for the most part, the southern seemed to prefer it that way as they grew up with nature and wished to preserve it for generations to come.

I can imagine industrialization in the proxy South with new investment from the coalition’s British, French, and other friendly nations. Such automation will provide incentives for gradual manumission in areas that don’t need slavery. I think it is barmy and foolish if great Britain would threaten the South to end slavery in every state or for its national government to meet great Britain’s demand. While the 1920s was a late time to abolish slavery, the last knowingly pro confederate prime minister was gone in 1895, so the institution will probably last as long as the South needs it to.
I don't see why Britain would try to force the Confederacy to abolish slavery (because the scenario which assumes they're willing to help them is already very different from their anti-slavery stance OOTL), but I also don't see much reason for them to push for its industrialization. As far as the "loving nature" part is concerned, I don't think that creating a soil-depleting cotton monoculture is proof of that, unless you're referring to something else.
After the American Civil War, the border states became much more pro csa particularly Kentucky. In 1862 southern victory with a Maryland invasion made it more likely that Baltimore and parts of Maryland would become CSA even if they didn’t 100% prefer it. This postwar underground railway will not be tolerated in slaveholding Kentucky. Also, how much the South gets in the west is kind of another question and another pod, perhaps. However, the underground railway silent film short told from a pro-slavery perspective might be amusing.
That doesn't make much of a difference, considering the Underground Railroad was already focused on getting escapees across the Ohio River. However, something that could cause problems is the trend of concentrating plantations in the Deep South, which started before the Civil War and was drastically accelerated by the possibility of all slaves within a 100-mile radius of any Union troop concentration attempting to escape. While the Railroad would continue running and find alternative routes if necessary, this could make hidden maroon communities of escapees living near the sites of their former enslavement more common.
European intervention against the Union butterfly the likeliness of European capital going to the north, because why would they wish to help the country they just humbled? Unless perhaps they were making the United States more dependent on Britain.
This is also dependent on the details of how this Confederate victory scenario is accomplished. In OTL, a major reason for Britain and France remaining neutral was the possibility of losing the substantial Union demand for their high-quality manufactured goods. Davis tried the "King Cotton" strategy of assuming that Europe would support the Confederacy by default for its cotton exports, but events proved this assumption to be false.
Well, if the latest country in the Americas to abolish slavery serves as an example, in Brazil, Black culture was always stigmatyzed and fought back, it was like this with Samba and lately with Brazilian Funk. Both of this genres were only accepted in the mainstream after being whitewashed and having it's themes stripped of political discussions. Maybe the South follows this way with Rock, R&B and etc.

Firstly they combat it as "cultural degeneracy" and after more white singers have adopted the genres, they start to propagandize it as "proof of the white superiority" in arts compared to Black "savagery" or even as a proof of the CSA as a "blend of cultures", if Brazil serves as an example again, the best way to fight oppressed groups is to make them feel as part of an union and not oppressed at all.

I doubt slavery would take so long to be abolished in the country, IMO the latest possible date for it to happen is the early 1900s. There would be too much political pressure from other countries and from the inside, as an abolitionist movement would inevitably form and the Black minority of ~10% would not be quiet forever. An segregationist state would follow, with many riots and rebellions happening, a Confederate version of the Troubles, probably holding to the 70s or 80s, when Civil Rights finally comes.

As for a Southern Hollywood, I think it might not exist one because there's no need to. The cinema production never focuses on one single place, rather going where the money goes, be it Jackson, Richmond, New Orleans, Houston or Tampa.

An interesting question regarding sports is if soccer would ever be popular in the CSA. I remember seeing in a Vox video that the sport never had the chance to take off in the US mainly because of administrative questions of the main soccer leagues and that could very well not happen in the South if they have a strong association from the start. I doubt it would be a powerhouse in World Cups, but maybe it could have some successes.