25.( 14) As shown in the figure, in the isosceles trapezoid ABCD, AB=4, CD=9, ∠ C = 60, the moving point P starts from point C and moves along the CD direction to point D, while the moving point Q moves along the DA direction from point D to the end point A at the same speed. When one of the moving points reaches the end point, the other moving point stops moving.

(1) Find the length of AD;

(2) Let CP=x, and when X is a value, the area of △PDQ reaches the maximum, and the maximum value is obtained;

(3) Question: Is there a point M on the side of BC that makes the quadrilateral PDQM a diamond? If it exists, please find out the point m and the length of BM; Does not exist, please explain why.