In the video linked, how does he select the face/vertice/whatever?
How does he select the top of the object to extend it upwards, at 2:15? Like you would a regular object? And how do I go into a side view/snap to view? if it is a script, how do I get it/where?

Looks like he used box select tool while in edit mode. tab to switch between object and edit mode then B key to select box select. Hit B twice for Brush select. use mouse to +/- the size of the brush

thanks, beginner, though you seem to be a lot better at blender than me, lol