If this is the alocasia thingy and not the buddha's hand citron, then yes, it's poisonous, although I don't know how much. Generally aroids have calcium oxalate (?) crystals in them which are a mouth and throat irritant and your cat's probably not likely to eat enough to really get hurt because of this. Eating a lot over a period of time causes kidney damage, but that doesn't seem to be generally likely. Only dieffenbachias and calla lilies are widely considered to be really dangerous, as far as aroids go. I think.

I'm guessing it'll need a lot of humidity. Also you might want to let it dry down a bit between waterings. This seems to be standard advice for most houseplants, and I don't think that would differ here (Unless maybe it was one of those species that tends to grow in rivers, but that's different, because flowing water and stagnant pot-moisture are different things).

I've never had luck with alocasias not completely falling apart on me. They turn orange for no apparent reason and just like, rot from the leaves inward. Apparently humidity causes this, somehow. This might also just be Alocasia x Poly 'African Mask' or whatever the black-and-white ones are, though.

Good luck!