First of all, you can’t spell something just based on hearing it because a /k/ sound can be a ‘c’ or a ‘k’, and a /s/ can be an ‘s’ or a ‘c’.

Yes you can. K isn’t often used in spanish except for loan words. C and S aren’t interchangeable in spelling they just sound the same when pronounced in certain phonemes. There are very specific rules about which letter is used in each phoneme. If you know spanish then you’d know this since they are some of the first lessons you learn about spelling.

Every other example you gave was a loan word.