Meetings of the Zoning Hearing Board shall be held at the call of the Chairman and at such other times as the Board may determine. 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. Upon the filing with the Board of an appeal, a request for interpretations or findings of fact concerning any contested ordinance or map, or of an application for a special exception or variance, the Board shall fix a time and place for a public hearing and shall, in the manner prescribed by its rules and the Planning Code, give public notice thereof, as well as due notice to the parties in interest, who shall include those persons whose properties adjoin the property in question. Any party may appear at a public hearing in person or by agent authorized in writing or by an attorney. The Chairman or Acting Chairman of the Board or the hearing officer presiding shall have power to administer oaths and issue subpoenas to compel the attendance of witnesses and the production of relevant documents and papers, including witnesses and documents requested by the parties. The Board or the hearing officer, as the case may be, shall render a written decision or, when no decision is called for, make written findings on the application within 45 days from the date of the completion of the hearing. The applicant shall be promptly notified of said decision or findings as provided by law.