The board of adjustment shall consist of five regular members, plus one additional member designated as an alternate who shall attend and serve only when one of the regular members is unable to attend for any reason, each to be appointed for a term of three years and removable for cause by the appointing authority upon written charges and after public hearings. Vacancies shall be filled for the unexpired term of any member whose term becomes vacant. One member only of the board of adjustment shall be appointed from the membership of the planning commission, and the loss of membership on the planning commission by such member shall also result in his or her immediate loss of membership on the board of adjustment and the appointment of another planning commissioner to the board of adjustment. After September 9, 1995, the first vacancy occurring on the board of adjustment shall be filled by the appointment of a person who resides in the extraterritorial zoning jurisdiction of the city or village at such time as more than two hundred persons reside within such area. Thereafter, at all times, at least one member of the board of adjustment shall reside outside of the corporate boundaries of the city or village but within its extraterritorial zoning jurisdiction. The board of adjustment shall adopt rules in accordance with the provisions of any ordinance adopted pursuant to sections 19-901 to 19-914. Meetings of the board shall be held at the call of the chairperson and at such other times as the board may determine. Such chairperson, or in his or her absence the acting chairperson, may administer oaths and compel the attendance of witnesses. All meetings of the board shall be open to the public. The board shall keep minutes of its proceedings, showing the vote of each member upon each question, or, if absent or failing to vote, indicating such fact, and shall keep records of its examinations and other official actions, all of which shall be immediately filed in the office of the board and shall be a public record.