How to draw the line throung many faces that are separated UV parts?

Situation: I have the cube and UV map for it. I want to draw the horizontal line going through all the side faces.

  1. How could I know while drawing that the point where i start it on another face is the place where it ends on the previous one?

    Example image, you see what i mean, the line doesn’t match on different faces.
    How to do it properly? is there any hints or methods?:mad:

  2. And second: when I unwrap the cube and select face how could I know where is it’s top or bottom? For example I draw the line through some faces on UV map and some of the parts turn 90 degrees angle or 180. Like this:

    Is there any hints for users in the UV’s window in Blender to mark face’s top side, left, right etc.:confused: