There is a standard specification for headstones as laid down in the Constitution Volume II Section 2:2:15. This means that any headstones erected in the churchyard will only require the consent of the incumbent. Non standard headstones and memorials will require a faculty.
The primary duty to maintain and repair headstones is the responsibility of the families of the deceased. However, the PCC also has a responsibility to users of the churchyard to ensure it is a well maintained and safe place to visit.
The Management of Churchyards Guidance and Policy Document contains useful information relating to headstones, memorials and tombs: Management of Churchyards