Short answers, pulled from the story.
The Cherokee signed a treaty of alliance with the Confederacy in October 1861 after Union troops abandoned positions in Cherokee territory and financial pressure mounted. Their existing cultural, trading, and legal ties to the seceding Southern states, combined with fear that Lincoln would open Indian Territory to white settlement, made Confederate alignment appear protective to many Cherokee leaders.
Stand Watie was a 3/4 Cherokee Confederate leader who began recruiting all-Indian Confederate units on the 1st of June, 1861. He was elected Chief of the Southern Cherokee Nation in 1862 and led primarily Native Confederate forces in the Indian Territory. He became the last Confederate general to end fighting, surrendering on the 25th of June, 1865, at Fort Towson.
The Keetoowah Society organized in opposition to Confederate support within the Cherokee Nation. It represented a faction that aligned culturally with the nationalist, largely Cherokee-speaking, anti-slavery segment of the population, in contrast to the pro-Confederate Gold Cloak Society.
William H. Thomas was a European-American who had been adopted Cherokee. He began recruiting Cherokees from the Quallatown, North Carolina area in May 1861, forming a unit that started as the Junaluska Zouaves and was later designated the 69th North Carolina Regiment, with 1,125 men total. The Legion guarded Appalachian mountain passes in western North Carolina and eastern Tennessee.
Eastern Cherokee suffered a severe smallpox outbreak, and Thomas and his followers fell into deep debt. In the west, Indian Commissioner D. N. Cooley exploited the division between Cherokee factions to confiscate Confederate Cherokee land, force the tribe to adopt their former slaves, and allow white settlement of Cherokee lands. The federal government also recognized the eastern and western Cherokee as separate tribes.
Approximately 3,000 of the Cherokee Nation's roughly 21,000 members served as Confederate soldiers. Their units included mounted rifles, volunteer cavalry regiments, artillery, partisan rangers, and infantry battalions operating primarily in the Indian Territory and in the Appalachian mountain passes.