1. Yes, California is horrid for a person's name.
Callie would be perfectly fine on its own, and I'd really take any spelling of it over California. :-/ BTW,
Kali looks like KAH-lee to me (and the association is not a nice one - click the link) but she'd probably get KAY-lee a lot.
Callie is the safest and most appealing, imo.
2. I see
Cassia like Marcia--she'll have to correct people, and even moreso because
Cassia is much less common than
Marcia, but if you like it, go for it. I don't care much for the "cash" sound in
Cassia, but it's not a bad name by any means, and I definitely prefer the
Cassia spelling over any other kre8tyv or more fonettik one. ;)