Given that \(\mathbf{a} = \begin{pmatrix} 2 \\ -2 \\ 1 \end{pmatrix}, \mathbf{b} = \begin{pmatrix} 2 \\ 6 \\ 3 \end{pmatrix}\) and \(\mathbf{c} = \begin{pmatrix} p \\ p \\ p+1 \end{pmatrix}\), find

(i) the angle between the directions of \(\mathbf{a}\) and \(\mathbf{b}\),

(ii) the value of \(p\) for which \(\mathbf{b}\) and \(\mathbf{c}\) are perpendicular.