Regarding stalling, ALL sweepbacks increase stalling angle as far as I recall. I'd have to go into the attic to dig out my text books to remember why!
Suseptability to spanwise airflow....some designs (Reynolds Number) more than others.
I think it fair to say for 707-planform aircraft, the swept fin is not greatly useful.
Oh, but it is, on aircraft with greater wing sweep (than the Comet, for example).
Two reasons.
Better yaw suppression and...if it was not swept, it would need to be either taller or broader, and in turn, the aircraft would have more difficulty meeting the certification criteria for positive spiral stability.
Many trade-offs in design.
Have a look at DP Davies book, 'Handling the Big Jets' as these issues (and a lot more) are explained in good detail.
Davies, more than any other one single individual, had a profound effect on certification for jet transport airplanes.