Answer
(a) Focus: $F(0,2)$
Directrix: $y=-2~~$
$Focal~diameter=8$
(b)
Work Step by Step
Equation of a parabola with vertical axis: $x^2=4py$
$x^2=8y$
$4p=8$
$p=2$
Focus: $F(0,p)=F(0,2)$
Directrix: $y=-p=-2$
$Focal~diameter=4p=8$