Q1: A square fulfils all the requirements of a rhombus; 2 pairs of parallel sides and all sides are of equal length. But none of a rhombus’ sides meet at 90°.
Q3: The figure is a rhombus. A rhombus has a pair of opposite sides equal in length, the other pair is not equal in length and one of the properties of a rhombus is that a pair of opposite angles must add up to 180°, therefore the figure is a rhombus.
Q4: No, I do not agree. The first reason is because the interior angles of a parallelogram are not 90°. Second reason is that all four sides of a parallelogram are not equal.