Some covens are tied together in fraternal relationships and acknowledge authority of a Priestess or Priest from whom orders are derived. Many are totally anonymous. A High Priestess or a Priest. No, but it is encouraged. Various traditions will demand other items.
Witches worship within a magick circle that is inscribed on the ground or floor.
The circle should be located so as to insure the privacy of the rituals. The Church and School of Wicca does not adhere to specific festival dates, understanding that these are based on solar and lunar events, not on a calendar's traditional needs. Major holidays are termed sabbats, and weekly or bi-weekly meetings are esbats. In case of death, the coven to which the Witch belongs should be contacted. Generally no restrictions.