Compute the characteristic polynomial of

$$A=\left(\begin{array}{ccc} 3 & -1 & 2 \\ 0 & 4-s & 2 s-2 \\ 0 & -2 s+2 & 4 s-1 \end{array}\right)$$

Find the eigenvalues and eigenvectors of $A$ for all values of $s$.

For which values of $s$ is $A$ diagonalisable?