Short answers, pulled from the story.
Estimates of civilian deaths in the First Chechen War range from 20,000 to 100,000. Most scholars and human rights organizations estimate roughly 40,000 civilian deaths, a figure attributed to Chechnya expert John Dunlop, while Chechen sources cited figures closer to 100,000. More than 500,000 people were displaced by the fighting.
Dzhokhar Dudayev was a former Soviet Air Force general who led the All-National Congress of the Chechen People. He declared Chechen independence from the Soviet Union after winning the October 1991 presidential election with 90.1% of the vote. He was assassinated by a Russian guided missile on the 21st of April 1996, but Chechen resistance continued under acting president Zelimkhan Yandarbiyev.
The Khasavyurt Accord was a ceasefire agreement signed on the 31st of August 1996 by Russian national security adviser Alexander Lebed and Chechen Chief of Staff Aslan Maskhadov. It required the withdrawal of all Russian federal forces from Chechnya by the 31st of December 1996 and deferred any final decision on Chechnya's political status until 2001. A formal peace treaty was subsequently signed by Yeltsin and Maskhadov on the 12th of May 1997.
Operation Jihad was a major Chechen counter-offensive launched on the 6th of August 1996, led by Aslan Maskhadov and Shamil Basayev. Around 1,500 Chechen fighters infiltrated Grozny and within hours surrounded Russian garrisons and the government compound. The operation also seized Argun and Gudermes, effectively reversing Russian territorial gains and precipitating the peace negotiations that ended the war.
The Samashki massacre occurred on the 7th of April 1995, when OMON and other Russian federal forces seized the border village of Samashki, killing up to 300 civilians. Federal soldiers conducted house-by-house searches, deliberately attacked civilian dwellings, shot residents, burned houses with flame-throwers, and threw grenades into basements where women, elderly people, and children were hiding. It has been described as the worst massacre of the war.
Russian military death figures vary significantly by source. The official Russian estimate was 5,500 killed, while the General Staff cited 3,826 killed with 1,906 missing. Independent researcher Pavel Milyukov estimated 5,391 dead, and the Committee of Soldiers' Mothers of Russia estimated as many as 14,000 Russian military deaths based on information gathered from wounded troops and soldiers' families. The Russian military was widely noted to have concealed its actual casualty figures.