Short answers, pulled from the story.
An improvised explosive device detonated near Tskhinvali wounding five Georgian police officers triggered artillery exchanges that escalated into full-scale war. This incident marked the opening of hostilities between Georgia and South Ossetia.
Russian heavy armoured columns passed the Roki Tunnel at around 16:00 MSK on the 8th of August 2008. By 17:00 MSK Russian tank columns surrounded Tskhinvali and began bombing Georgian positions.
The war displaced 192,000 people including 127,000 within undisputed parts of Georgia and 65,000 within South Ossetia or from South Ossetia to North Ossetia. As of May 2014 20,272 persons remained displaced with return blocked by de facto authorities.
French President Nicolas Sarkozy negotiated a ceasefire agreement signed by six parties on the 12th of August 2008. Russian President Dmitry Medvedev signed the agreement on the 16th of August 2008 after which hostilities did not immediately end.
Russian President Dmitry Medvedev issued orders recognizing independence on the 26th of August 2008 stating recognition was the only possibility to save human lives. The United States France and other international bodies condemned this move for violating Georgia territorial integrity.