Rule number one in mechanics: draw a graph! Even if one is given.
Write down what you know, v for final velocity, u for initial velocity, t for time, a for acceleration and s for displacement.
For SUVAT you'll need 3 known variables and the one you need I usually write it down as (in your case would be) s = ?.
You know a, u, v of the object. Select the equation with the 4.
v= u + at
s = 0.5t(v + u)
v^2 = u^2 + 2as
s = ut + 0.5at^2
iii) is the only one that I can see being a problem to you so here's a hint:u is given, v is taken from ii), a is given, s is given. So you can pick any equation for this, use multiple equations to verify your result.
Think about the direction. If you treat upwards as positive i.e. v = +3m/s then acceleration that's downwards (due to gravity) will obviously be...