Short answers, pulled from the story.
The assault on Königsberg ran from the 6th to the 9th of April 1945, though the wider siege of the city began in late January 1945. The German garrison surrendered shortly before midnight on the 9th of April after three days of intense fighting.
Joseph Stalin ordered Marshal Konstantin Rokossovsky to destroy the German forces trapped in East Prussia, and Ivan Bagramyan led the 1st Baltic Front that cut the region off from Germany. Marshal Aleksandr Vasilevsky twice demanded the German garrison's surrender, while General Otto Lasch commanded the defense and ultimately negotiated the surrender.
General Otto Lasch decided on his own initiative that further resistance was futile after German defense coordination collapsed on the 9th of April 1945. He had already asked Hitler's headquarters for permission to surrender the previous evening and been told to fight to the last soldier.
Roughly 200,000 civilians were trapped inside Königsberg when Soviet forces surrounded the city in late January 1945. Rations were cut to 180 grams of bread a day, and about 2,000 women and children a day chose to cross the ice of the Vistula Lagoon toward Pillau rather than remain.
The National Committee for a Free Germany, or NKFD, was made up mostly of German prisoners of war and sent Combat Groups to fight alongside the Red Army wearing captured Wehrmacht uniforms. On the 22nd of March 1945, a company of 58 men led by Lieutenant Alfred Peter returned from an operation near Königsberg with 35 captured German soldiers.
Almost 80 percent of the city was destroyed, first by Royal Air Force bombing in August 1944 and then by Soviet shelling during the April 1945 assault. Königsberg was renamed Kaliningrad after the war and resettled mainly by Russian settlers, and it remains a Russian exclave today, bordering Poland and Lithuania.