Child support in Canada is re-assessed every year. If the income goes up, child support goes up. if income goes down, child support goes down. The child support tables are guidelines only and in many cases judges award more in child support then the tables state. How do I know ?? Guess what.
All of your above points do not matter. A judge has the final authority. If you don't like the judgement - appeal. If you exhaust all legal avenues you pay. If you don't pay or obey the judgement you are in contempt of court. Simple as that.
Laws are there for a reason. You might not like them or how the judge interprets them. If no-one would obey the court we would have anarchy.