Deep freezing film will not harm it. Let it thaw out for 2 hours upon removal
before opening the film package.
Film kept at -15°c can be kept indefinitely, though background radiation will eventually affect it. "How long is "indefinite"? Well, how long is a piece of string!? Not a particularly noteworth film burner, I'm still using Velvia 50 from 1997, Provia 100F from 1998, and Ilford Delta from 2000 when they were all cheaper than they are now!
One thing to remember is
never to put a camera in the fridge or deep freeze! Sounds silly to mention it? Of course, and silly people do just that with this "cold film" fetish.
Holidays not finished for me. Just back home to restock then departing again Tuesday.