Short answers, pulled from the story.
Gopal Krishna Gokhale was an Indian political leader and social reformer who lived from the 9th of May 1866 to the 19th of February 1915. He was a senior leader of the Indian National Congress, founder of the Servants of India Society, and the political mentor of Mahatma Gandhi. He led the moderate faction of Congress, advocating reform through constitutional engagement with British institutions rather than agitation.
The Servants of India Society was founded by Gokhale in 1905, when he was at the height of his political influence as Congress president. Its purpose was to expand Indian education and train Indians in their civil and patriotic duties. The Society organized mobile libraries, founded schools, and provided night classes for factory workers. It still exists, though with a small membership.
The 1907 Congress session at Surat ended in a physical breakdown between moderate and extremist factions. A dispute over the presidency, with Gokhale backing Rash Behari Ghosh and Tilak backing Lala Lajpat Rai, led to chairs being smashed and shoes and sticks being thrown. When the crowd moved toward Tilak on the dais, Gokhale stepped in beside him to protect him. The session collapsed and Congress split into two rival groups.
Gokhale argued that the indenture contract was structurally unfair, that workers were inadequately protected by authorities, and that the system produced a mounting number of suicides. In 1910, he successfully moved a resolution in the Imperial Legislative Council that ended indentured migration in Natal. In 1912, he moved a further resolution for total prohibition of indentured labour; that failed, but his campaign helped bring about the abolition of the system in 1920.
Gandhi called Gokhale his mentor and guide in his autobiography, describing him as "pure as crystal, gentle as a lamb, brave as a lion and chivalrous to a fault." After Gandhi returned from South Africa, Gokhale provided him with personal guidance and grounding in Indian political life. Gokhale visited Gandhi in South Africa in 1912. Despite this mentorship, Gandhi ultimately rejected Gokhale's faith in Western institutions and chose mass agitation over constitutional reform.
Gokhale was a moderate who believed India should pursue self-government through constitutional means and cooperation with British government institutions. Tilak was a nationalist who favored protest, boycott, and agitation, and rejected the idea of British interference in Indian affairs even when reform was the goal. Their disagreement over the Age of Consent Bill and the Congress presidency eventually led to the open split at Surat in 1907.