I haven't had any problems with smell. They smell like wood because they are made out of wood. That is normal. After they have been lit fully= no smell.
They do break and they splinter on occasion. It's normal. I don't know about "terrible smells " and your reference to carbon monixide doesn't make sense. (because carbon monxide is a silent killer, you can't smell it) but it has a natural wood burn smell.
GLaDOS: "You euthanised your faithful companion cube more quickly than any test subject on record. Congratulations!"