1. PF3 will use the first one in the list when there's multiple entries
Hmmm, my first flight testing this, and PF3 didn't do that. Here are my entries for Austin, KAUS, in PF3_FS9_Freq.dat:
KAUS,0,0,"Austin Bergstrom Intl"
KAUS,3,122.95,"AUSTIN BERGSTROM INTL"
Yet, at the runway, ATC asked 'Contact tower on 118.22' (the identifier '6'). I was expecting 121.00, which would have worked in XP.
Maybe I need to delete any frequencies in the dat file which are not in XP11 (like 118.22, above)? Would deleting those have any 'undesirable consequences' that you can foresee?
Attach a log file, in case it's needed.