Functions - Piecewise-Defined Functions

It is given that \[\mathrm{f}\left( x \right)=\left\{ \begin{matrix} 4-2x\text{ for}\hspace{0.5em}0<x\le 2, \\ -{{\left( x-4 \right)}^{2}}+4\text{ for}\hspace{0.5em}2<x\le 4, \\ \end{matrix} \right.\]

and \(\mathrm{f}(x) = f(x + 4)\) for all real values of \(x\).

1. Evaluate \(\mathrm{f}\left( 17 \right)+\mathrm{f}\left( -8 \right)\).
2. Sketch the graph of \(y=\mathrm{f}\left( x \right)\) for \(-10\le x\le 7\).