Girl

John Owens

SOLUTION:

Each song is by the name of a musical group or solo act with a woman's name in the artist's name. Furthermore, each of these names is the first name of a First Lady (wife of the President of the US, clued by "number one girl").

The nth president maps to number n; mod with 26 and take the appropriate letter of the alphabet.

letter## First LadyArtistSong
P16 Mary Todd LincolnPeter Paul and MaryPuff the Magic Dragon
R18 Julia Dent GrantJulia FordhamHappy Ever After
E31 Lou Henry HooverLou ReedTake a Walk on the Wild Side
Z26 Edith Kermit Carow Roosevelt Edith PiafLa Vie En Rose
L12 Margaret Mackall Smith TaylorMargaret WhitingMoonlight in Vermont
A27 Helen Herron TaftHelen ReddyI Am Woman
C29 Florence Kling HardingFlorence Foster JenkinsBiassy
K11 Sarah Childress PolkSarah McLachlanIce Cream
IAnna Tuthill Symmes HarrisonAnna VissiEverything I Am
N14 Jane Means Appleton PierceJane's AddictionBeen Caught Stealing
GRachel Donelson JacksonRachel LoyThe Same Man
O41 Barbara Pierce BushBarbara MandrellSleeping Single in a Double Bed
N40 Nancy Davis ReaganNancy SinatraThese Boots are Made for Walking
E31 Lou Henry HooverLou BegaMambo Number 5

The message indicates "PREZ LACKING ONE", indicating a first lady; the only unmarried president was James BUCHANAN.

Comments in the mp3 id3 tags spell out "UNPOISSONROUGE" (one letter per mp3 file) or "a red fish", aka "red herring".

Answer: BUCHANAN