The equation says ClO subscript 3 with a negative charge. Is the answer key ClO subscript 4 with a negative a typo? The results are the same, but I'm just checking.

I honestly am not understanding the concept behind half reactions, is this just a term to break down the equation for redox reaction?

These acids do not have hydro- as a prefix... is that because they contain polyatomic ions? Would it be incorrect to put hydrosulfuric and hydrocarbonic acid?