Short answers, pulled from the story.
The Taforalt cave in Morocco is possibly the oldest known cemetery in the world. It held the remains of at least 34 Iberomaurusian individuals, the bulk of whom have been dated to between 15,100 and 14,000 years ago.
A graveyard primarily refers to a burial ground within a churchyard, while a cemetery is a place specifically designated as a burial ground independent of a church. The word cemetery derives from the Greek word for sleeping place and originally applied to the Roman catacombs.
The first garden cemetery was Père Lachaise Cemetery in Paris, which opened in 1804. The landscaped cemetery concept had been proposed as early as 1711 by British architect Sir Christopher Wren but was not widely adopted until overcrowded urban churchyards made it necessary.
The shift was driven by rapid population growth during the Industrial Revolution, repeated outbreaks of infectious disease, and the 1831 cholera epidemic, which killed 52,000 people in Britain alone. Parliament acted in 1832 to encourage large municipal cemeteries outside London and closed all inner London churchyards to new burials.
A columbarium wall is a structure, typically of brick construction, containing a rectangular array of niches that hold cremated remains. Each niche holds a small plaque roughly 15 cm by 10 cm, and niches are usually placed between 1 and 2 metres above ground so the plaques can be read easily.
Stones are left on Jewish grave headstones as a show of respect and to symbolise that love, honour, and memory endure. Flowers are fleeting; the permanence of stone carries the symbolic meaning. As a general rule, flowers are not placed at Jewish graves.