1) A relationship immortalized by Tommy Lee Jones and S. Epatha Merkerson in the Daniel Day Lewis biopic
Lincoln.
2) Don't worry about it.
Other than settling accounts with the British Empire (reparations, which ITTL may well be larger than IOTL), only "Imperial"
Mexico stands as an issue for the United States🤬😤 with
any power in Europe.
3)
VERY UNLIKELY to see an alliance or amalgamation between Labor factions and the Populist Party. The Populists never made inroads into the Northeast or West Coast and did poorly in the Great Lakes.
While ITTL they are much more likely to make deep inroads into the Deep South, their inherent anti-"Papist" bigotry makes it impossible for them to ever be taken seriously by political forces dominated by labor unions that have among them teeming numbers of Roman Catholics (Irish, Italians, Germans, Poles, etc, etc, etc...).
4) Good idea. Just enough to show the butterfly effects of TTL on Europe, and
those butterfly effects that later on touch upon the United States. The latter effect being muted by the expected long term (33 years?) American Isolationism seen with America's obsession with internal development. Or to put it more bluntly, the American People won't care for the next couple of generations over matters going on in the outside world, being so busy as they will be. Namely, conquering the Old West and slaughtering our Native Americans.
After all, there's little to indicate that there's been any real changes (IIRC) to TTL regarding White America's treatment of its native populations. The Sand Creek Massacre, frex, will probably happen, on schedule, and tragically, unchanged.