Crossword puzzle clue "it follows a line"

1929 #1 hit whose title follows the line "Now he's gone and we're through"

It follows a line

Follows the party line?

Hymn whose title follows the line "When I die, Hallelujah, by and by"

It follows a dot in many on-line addresses

It follows a mine 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