Crossword puzzle clue "first in line often"

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

First-in-line's line

First in line, often

Speaker of the first line of the first episode of "South Park"

Film character whose first line is "First day of school!"