You found the velocity required for question 1,

for

This is the velocity for all the points greater then t. It doesn't ask for any more then this, and if you notice, in the second question it asks us to graph the above function. That is how you'll know what the values will be.

Note though that,

so

and

For question 2,

We need to graph

You can either do this via tech (i.e. tx calculator or an online grapher) or you can notice that this graph is really just a translated version of

You know how to draw

right? So draw that on paper for the given period, then draw the negative of that because we have

then after doing that, add 1 to account for our constant. This will get you the graph,

For Question 3,

Sketch this in the same way as the other one