Short answers, pulled from the story.
The Central Committee of the Bulgarian Workers' Party and general staff of the People's Liberation Revolt Army commenced planning on the 5th of September. Coordinated actions between partisans, BWP combat groups, and pro-Fatherland Front army detachments assumed power during the night of the 8th to the 9th of September.
Premier Konstantin Muraviev formed a new government on the 2nd of September 1944 that was subsequently overthrown by communist forces. Prime Minister Muraviev and three royal Regents Prince Kiril, Bogdan Filov, and Nikola Mihov were arrested immediately after the Fatherland Front announced control on the 9th of September morning at 6:25 AM.
Eight thousand one hundred thirty political prisoners were released from jails during this period. Political prisoners were also released from prisons in Pleven, Varna, and Sliven starting the 6th of September and continuing through the 7th of September.
King Simeon II remained child ruler theoretically but regents deposed practically after the referendum about monarchy destiny held nationwide across Bulgaria on the 8th of September 1946. Results declared Bulgaria People's Republic on the 15th of September 1946 following successful vote.
By the 5th of September 1944, the Soviet Union officially declared war on Bulgaria, catching Western Allies by surprise. Communist leaders began planning a coup d'état on that same day to overthrow Muraviev's government.