Answer
$a). 155 m/s$
$b). 2225.76m$
$c). 28.72s$
Work Step by Step
a). $v^{2}=0+2aS$
$v^{2}=2\times 12\times 1000$
$v=155m/s$
b). $0=155^{2}-2\times 9.8\times h$
$h=1225.76m$
Total maximum height=$1225.76+1000=2225.76m$
c). For first 1000m of flight,
$t=\frac{v-u}{a}=\frac{155-0}{12}=12.9s$
Next,
$t=\frac{v-u}{g}=\frac{0-155}{-9.8}=15.82s$
Total time taken $=12.9+15.82=28.72s$