All of the questions you are asking are explained in the Fallout Wikia.... just go look it up...
Oh?
Sorrows
Spoiler The Sorrows are a tribe living in the Zion National Park area of the former Utah state, in the up-coming Fallout new vegas Add-on, Honest Hearts.
Doesn't explain much at all.
Church of Jesus Christ of Latter-Day Saints
Spoiler In 2246, the Mormon missionary Joshua Graham encountered two Followers of the Apocalypse, Calhoun and the man who would come to be known as Caesar. As one of the founders of Caesar's Legion, the Mormons are understandably embarassed about Graham, and are loathe to discuss him.
By 2281, the Mormons of New Canaan control most of the trade routes north of New Vegas, and impose heavy taxes on companies such as the Crimson Caravan, making NCR expansion in the area difficult.
A bit more meaty but still not enough to give a clear view of what their role in it is
White Legs
Spoiler The White Legs is a tribal living in the area of Zion National Park in 2281.
That sure explains a lot.
Daniel
Spoiler Daniel lives in the Mojave Wasteland in 2281. According to the Honest Hearts achievements, he will play a crucial role in the Sorrows tribe.
Uh-huh, who let this piece of speculation be on a wikia entry?
It's not certain he's going to play a crucial role. He might just be the chef and needs to be resupplied for a chili con carne festival.
May my Hand Forget its Skill
Why?
In a foreign land
Spoiler Scout the Zion Valley for signs of the White Legs.
White Legs might be a bit more hidden?
They're at first opposition?
Again, not enough to base facts on.
O Daughter of Babylon
Why?
For what reason?
Is there a diplomatic solution?
Is this optional?
I wouldn't say that the wikia knows any more than I already did.