on the subject of winter trials tires I would stay away from the Maxxis Creepy Crawler and Monty Eagle Claw. They both use the same rubber compound which actually freezes once you get below -20 or so. When the tires are frozen they crack a bunch and wear quickly while offering nearly zero grip.
I have had good results riding a Luna tire down past -40, I have one studded for winter trials but really haven’t used it much the last few years. Lost of people don’t like the Luna in summer though (I prefer a MEC)
for more information on trials tires check out this thread, more than you ever wanted to know about 19" tires.
on second thought, ignore all that. ride what you got/get. If you loose some grip when it’s -20 you loose some grip and the cracks don’t really affect the tires performance, it just looks bad. How often are the kids going to be riding when it is that cold out anyway?
oh and don’t worry about the pedals. Those new plastic bodied pedals can probably take more falls than traditional metal bodied pedals since they absorb a bit of the shock of hitting a rock etc.