Given that \(y = 7 - px - x^2 = 16 - (q + x)^2\) for all values of \(x\), where \(p\) and \(q\) are both positive,

- calculate the values of \(p\) and \(q\),
- state the maximum value of \(y\) and the value of \(x\) at which it occurs,
- find the range of values of \(x\) for which \(y\) is positive.