Coordinate Geometry - Area of Rectilinear Figures

Solutions to this question by accurate drawing will not be accepted.

The diagram shows the kite \(PQRS\). Given that the coordinates of points \(P\), \(Q\), \(R\) and \(S\) are \((4, 5)\), \((-4, -4)\), \((a, b)\) and \((0, 7)\) respectively where \(a\) and \(b\) are constants, find

1. the coordinates of \(R\),
2. the equation of \(QP\),
3. the area of \(PQRS\).