Jordan canonical form of a matrix

Consider the following matrix:
	\[
		A=\begin{bmatrix} 0 & 1 & 0 & 0 \\ 0 & 0 & 1 & 0 \\ 0 & 0 & 0 & 4 \\ 0 & 0 & 0 & 0\end{bmatrix}.
	\]
\begin{enumerate}[label=\alph*)]
	\item Determine the characteristic and minimal polynomials of $A$.
	\item Find a basis for ${\bf R}^4$ consisting of generalized eigenvectors of $A$.
	\item Find an invertible matrix $S$ such that $S^{-1}AS$ is in Jordan canonical form.
	\item Determine a Jordan canonical form of $A$.
	\end{enumerate}