Relative to an origin O, the position vectors of points A and B are given by

\(\overrightarrow{OA} = \begin{pmatrix} 3 \\ -6 \\ p \end{pmatrix}\) and \(\overrightarrow{OB} = \begin{pmatrix} 2 \\ -6 \\ -7 \end{pmatrix}\),

and angle \(AOB = 90^\circ\).

(i) Find the value of \(p\).

The point C is such that \(\overrightarrow{OC} = \frac{2}{3} \overrightarrow{OA}\).

(ii) Find the unit vector in the direction of \(\overrightarrow{BC}\).