Crossword puzzle clue "found a line"

Add vertical line 13 (word 3) and vertical line 3 (word 1) together and enter the answer to the resulting clue on this line

Add vertical line 9 (word 2) and vertical line 7 (word 2) and enter the answer to the resulting clue on this line

Add vertical line 1 (word 1) and vertical line 15 (word 3) and enter the answer to the resulting clue on this line

Add vertical line 15 (word 1) and vertical line 1 (word 3) and enter the answer to the resulting clue on this line

It can be found in a conger line?

What could be found at the 50 yard line?

Source of the line "Midway upon the road of our life I found myself within a dark wood ..."

Where the bottom line may be found