Building a Musjid on someone elses land

Q: A piece of land was donated by a man for a qabrastan. 30 years after his death, a masjid was constructed within the space of the donated land by a division of a muhalla relating to the internal disagreement of some matters. Is it permissible to recite salaah in that masjid?

Q: If someone builds a masjid on the property that is owned by the government, then is it permissible for the government to demolish some part of it for the extension of a road?

Q: Is common plot lawful to build a Musjid on?