As Piet said
NAG (or NAGr.) = Nahaufklärungsgruppe - Tactical (short range) Reconnaissance
Tactical recce units were originally designated (H) for Heer.
FAGr. = Fernaufklärungsgruppe - Strategic (long range) Reconnaissance
1.(F)/122 would be the 1st long range reconnaissance staffel of aufklärungsgruppe 122
Long range night reconnaissance units were designated like this example 2.(F)/Nacht
Check the following link for detailed data on Lw recce units
click Air Units > Reconnaissance Units
Does your list of recce sorties mention the pilots who flew each sortie?