How can I select one point of the List Item?

Hi to everyone!

First:

I've been trying for hours to select just one point of the list item. Does somebody know how to do it?. I want that to then move it through the Z plane. 

Second:

When it selected (a single point) if I move the selected point through the Z axis (or Z plane) does the geometry of the surface will change? or in order to make it change I will have to do a new surface from the new point configuration?

I really need help with this, Thanks for your help

Diego