Short answers, pulled from the story.
The All India Congress Committee (AICC) is the central decision-making assembly and presidium of the Indian National Congress. It formulates party policy at the national level, sets electoral strategy, elects the Congress President, and elects the Congress Working Committee, which is the party's apex governing body.
The AICC took on its modern institutional form after the Nagpur Session of 1920, when a new constitution was adopted transforming the Congress into a mass-based organisation with elected representatives from Provincial Congress Committees. The Congress itself was founded in 1885 but initially operated through annual meetings without a permanent central structure.
The AICC headquarters is currently at 24 Akbar Road in Delhi, just behind 10 Janpath. Before that it was at 7, Jantar Mantar Marg in Delhi, and before independence its original headquarters were at Swaraj Bhavan in Allahabad. The move to 24 Akbar Road occurred after the 1969 Congress split under Indira Gandhi.
Mallikarjun Kharge serves as the Congress President and head of the AICC. He also holds the position of Leader of the Opposition in the Rajya Sabha.
The AICC can have as many as a thousand members. These members are delegates elected or nominated by the state-level Pradesh Congress Committees, which themselves draw representation from district and panchayat-level party units.
The institutional records of the AICC are held in the Archives at the Nehru Memorial Museum and Library, located at Teen Murti House in Delhi.