Short answers, pulled from the story.
The war grew from Russia's desire to recover territorial and naval losses from the Crimean War of 1853-1856, reclaim rights to a fleet in the Black Sea, and support independence movements among Balkan nations under Ottoman rule. The Bulgarian Uprising of 1876 and the massacres that followed, in which up to 30,000 people were killed, created the public and diplomatic conditions that allowed Russia to finally act.
Romania, Serbia, and Montenegro formally proclaimed independence from the Ottoman Empire as a result of the war. Bulgaria emerged as an autonomous principality after nearly five centuries of Ottoman domination dating from 1396. Greece later annexed most of Thessaly and Arta through the Convention of Constantinople.
The Siege of Plevna lasted 145 days, from July to the 10th of December 1877. Ottoman commander Osman Nuri Pasha held the city with approximately 15,000 troops, repelling two major Russian attacks with heavy Russian casualties. The siege ended on the 10th of December when Osman Pasha attempted a breakout across the Vit river, was wounded, and the following day surrendered the city and his sword to Romanian colonel Mihail Cerchez.
During the war, Ottoman forces found the Red Cross emblem too reminiscent of the Crusades and replaced it with the Red Crescent on their military medical facilities. Both Russia and the Ottoman Empire had signed the First Geneva Convention of 1864, which recognized only the Red Cross. The Red Crescent was later ratified as an official protected emblem by the Geneva Conventions in 1929 and again in 1949.
In January 1878, Armenian Patriarch of Constantinople Nerses II Varzhapetian approached Russian leadership seeking treaty guarantees for self-administration in Armenian-inhabited provinces. His efforts resulted in Article 16 of the Treaty of San Stefano, which pledged reforms and security for Armenians. At the Congress of Berlin, this article was weakened into Article 61, which removed all reference to Russian troops remaining as a guarantee of those protections.
Januarius A. MacGahan was an American journalist hired by The Daily News to report first-hand on the massacres during the Bulgarian Uprising of 1876. His dispatches, published across the paper's front pages, turned British public opinion against the government's pro-Ottoman policy and contributed to the diplomatic conditions that enabled Russia to enter the war.