I can't help you with the expired vs. new film (I've only ever bought new film, although I'm sure some of my "new" film is expired by now
), but I just wanted to say you'll have fun with your TLR. I've got a Seagull TLR, and although I haven't used it much lately, it was always a lot of fun to play with. I really like the square format, too. Maybe one day I can afford a 6x6 Hasselblad before I die.
