Creating die lines in illustrator

I have been doing some research on creating die lines in illy but I have some unanswered questions: (using a standard box as an example)

1. If I want to indicate a fold (dotted line) at the base of a tab, do I create a dotted stroke across the fold, leaving an open path with the end anchor points overlapping the shape of the tab at the base?

2. Is the die line for a basic box one shape (closed path) with fold line strokes (open paths) overlapping the shape? Or are packages made from a bunch of different shapes (individual closed paths) all touching each other (overlapping sides) where each shape would be a section of the box?

4. Do the fold lines go on a separate layer from the cut lines?

I haven't been able to find a tutorial to create the die line from scratch by just going off measurements, so my questions are in regards to using the pen tool and shapes to get to the final image of the die.

Thanks!