yes, you are correct that 675 cells are actually zinc air. in that case, they should be fine, and I presume better priced than Wein air cells.
Yep, the 675s put out a steady 1.40v and are MUCH cheaper than the Weins. Even at a pharmacy, you can buy a six-pack for about the same price as one Wein. If you've got a Costco nearby, I recommend you buy your 675s there. You can buy a card of 48 batteries for less than $10. For that price, I just always keep a portion of a card in my camera bag and replace the batteries as necessary. I have found that 1.4v is so close to 1.35v that my cameras' meters are not affected by the very slight difference in voltage.
Yes, the zinc-airs don't last very long. Tops is around 9-10 months. But they're so cheap, who cares? Also, the zinc-air discharge profile is almost exactly identical to that of the original mercury cell batteries, which is reason enough for me to use them in preference to all others.