Isosceles triangle extended to a kite

The diagram shows an isosceles triangle \(PQR\), where \(PQ=QR\) and the line segment \(QR\) is parallel to the \(y\)-axis. Point \(P\) lies on the \(y\)-axis and the equation of the line \(PR\) is \(x+3y=42\). Point \(Q\) is \((-9,\ k)\), where \(k\) is a positive constant.

1. Find the coordinates of \(P\), \(Q\) and \(R\).[4]
2. Given that the point \(S\) is such that \(PQRS\) is a kite and the line segment \(RS\) is parallel to the \(x\)-axis, find the coordinates of \(S\).[4]
3. Find the area of the kite \(PQRS\).[2]