In reply to joekoruk:
I also have tiny feet, although at 2.5 not quite as small as your wife. Most of my day to day shoes are 34 or 35 in european sizes.
Many people find they like their boots slightly bigger for winter anyway - for me a 36 or even 37 is fine and my actual shoe size usually feels too small with my preferred hiking socks on. This enables me to use the footbeds I want to make the comfortable, and wear my preferred socks. I also don't start banging my toes on the ends when my feet have swollen slightly at the end of the day.
Oversizing is fine, but the main pitfall is heel rub. I have found it is important to try lots of pairs on to make sure that even if the boot is a little large in the toe, the heel stays firmly in place. Different boots have different shaped heels, so take the time to find something that fits your wife's heels. There are also some lacing techniques you can use to help with this.
Regarding crampons, I have found that Petzl Vasaks or Sarkens work well for me, but obviously this may depend on the boot. For something more technical, I have heard good things about the BD Cyborg on small boots, but haven't tried it. I often have to cut the end off the bar to prevent it from sticking out the back. This obviously means you can't return them, so be really sure they are what you want before you take a hacksaw to them!