1. The number of directors attending the board meeting meets the requirements. The shareholders' meeting of a joint stock limited company can only be held if more than half of the shareholders are present; It is invalid for director f and director g to entrust others to attend the board meeting. Director f needs written authorization, and director g should entrust other directors, not people other than directors.

2. The increase or decrease of directors and the revision of articles of association are the contents decided by the shareholders' meeting, and the board of directors has no right to decide.

3. Do not meet the requirements. Because the entrustment of director F and director G was invalid, director E didn't attend, and director B was right, so 3/7 agreed, which didn't meet the requirement 1/2.

4. Supervisors attending the meeting need not sign. Because all the directors attending the board meeting signed it to clarify the directors' resolution responsibilities and prevent abuse of power.