Given the complex numbers $z_1=3+2$i and $z_2=-1+i,$ compute

$($a$)z_1+z_2$

$($b$)z_1-z_2$

$($c$)z_1{z}_2$

$($d$)\frac{z_1}{z_2}$

$($e$)$ polar form of $z_1$ and $z_2$