Short answers, pulled from the story.
Harishchandra is a legendary king of the Solar dynasty, celebrated across texts including the Aitareya Brahmana, the Mahabharata, the Markandeya Purana, and the Devi Bhagavata Purana. He is regarded as the archetype of absolute truthfulness and is described in the Mahabharata as the only earthly king to find a place in the assembly of gods.
Harishchandra surrendered his entire kingdom, sold his wife Shaivya and their son Rohitashva, and agreed to work as a slave at a cremation ground in the holy city of Kashi, all to honor a donation he had pledged to the sage Vishvamitra. He collected fees for cremations until the deities, led by Yama and accompanied by Vishvamitra, appeared and praised his steadfastness.
In the Aitareya Brahmana version of Harishchandra's legend, the king's son Rohita substituted a man named Sunahshepa in place of himself for a human sacrifice owed to the deity Varuna. Sunahshepa prayed to the Rigvedic deities and survived; his prayers also cured Harishchandra of the stomach illness Varuna had inflicted on the king. The sage Vishvamitra subsequently adopted Sunahshepa.
Raja Harishchandra, released in 1913 and written and directed by Dhundiraj Govind Phalke, was the first full-length Indian feature film, and its subject was the legendary king Harishchandra. The story of Harishchandra also provided the basis for Ayodhyecha Raja in 1932, the first talkie of Marathi cinema, directed by V. Shantaram.
Harishchandra Ghat is the name of the cremation ground in Varanasi, the city known in ancient texts as Kashi, where the legendary king Harishchandra worked as a slave collecting fees for cremations. It is named in memory of the king's ordeal at that site.
Satya Harishchandra, the 1965 Kannada film directed by K. V. Reddy and starring Dr. Rajkumar, was awarded the President's silver medal for Best Feature Film in Kannada at the 13th National Film Awards. The film is considered a milestone in Kannada cinema and was later the first South Indian film to be digitally coloured, with the coloured version released in April 2008.