Short answers, pulled from the story.
The Battle of Friedland was fought on the 14th of June 1807 between the French Empire under Napoleon I and the Russian Empire under General Levin August von Bennigsen. It was a decisive engagement of the War of the Fourth Coalition, resulting in a French victory that ended the war. The battlefield is located in present-day Kaliningrad Oblast, near the town of Pravdinsk, Russia.
The Russian army suffered at least 20,000 casualties at Friedland, representing over 40 percent of its soldiers on the battlefield. An unknown additional number died drowning in the Alle River during the chaotic retreat. French casualties numbered approximately 10,000.
Bennigsen trapped his own army by concentrating all his pontoon bridges at the bottleneck village of Friedland, leaving roughly 50,000 men on the west bank of the Alle River with no room to maneuver. He also underestimated how quickly Napoleon could mass 80,000 troops, and poor health led him to stay at Friedland rather than retreat while he still could. Marshal Lannes's expert delaying action held Bennigsen in place until Napoleon arrived in force.
The Treaties of Tilsit required Russia to join the Continental System against Britain and to withdraw forces from Wallachia and Moldavia, while surrendering the Ionian Islands to France. Prussia suffered far harsher terms: Napoleon stripped roughly half of Prussian territory, creating the Kingdom of Westphalia under his brother Jerome and the Duchy of Warsaw under the King of Saxony.
The two emperors held their initial peace meeting on a raft anchored in the middle of the River Niemen, at the town of Tilsit. Alexander reportedly opened by saying he hated the English as much as Napoleon did, to which Napoleon replied they had therefore already made peace. The negotiations that followed lasted several days and included reviews of each other's armies.
Yes, Leo Tolstoy referenced Friedland in War and Peace as a pivotal event, though he did not describe the battle directly. The board wargame Friedland 1807 is also based on the engagement.