Short answers, pulled from the story.
The Pan-European Picnic took place on the 19th of August 1989. This event was based on an idea by Otto von Habsburg to test the reaction of the Soviet Union and Mikhail Gorbachev to an opening of the border.
Günter Schabowski announced that the new travel regulations would take effect immediately without delay at 18:53 CET. He had not been involved in the discussions about the new regulations and received a note from Egon Krenz announcing the changes without further instructions.
Harald Jäger allowed guards to open the checkpoints and let people through with little or no identity-checking at 22:45 on the 9th of November 1989. No one among the East German authorities would take personal responsibility for issuing orders to use lethal force against the crowds.
The demolition of the Wall was completed in 1994 after beginning on the evening of the 9th of November 1989. The East German Border Troops officially began dismantling the Wall on the 13th of June 1990, producing around 1.7 million tonnes of building rubble.
French President François Mitterrand and British Prime Minister Margaret Thatcher both opposed the eventual reunification of Germany due to fears of potential German designs on its neighbours using its increased strength. Margaret Thatcher privately confided to Soviet General Secretary Mikhail Gorbachev that she wanted him to stop it.