Ok put it this way. If you're good, you're going to succeed and get a job anyway. It doesn't matter if the employment rate for what you're doing is like 40% - it's hard but it's possible. So don't just be deterred because everyone says it's hard.
To answer your specific questions (out of sequence)..
Commerce has a large part of Maths. There are core units you need to do which will inevitably require maths. You get to learn a lot about principles to do with transactions, markets, economies etc so I would put it under the massive umbrella of "Business and Corporations" but nothing much about the "human" side of things - eg langauges, politics, philosophy, psychology etc. These are very technical in nature.
I do Arts and I can tell you that I am loving my course. But fair enough, I am only first year. But don't give in to generalisations - I don't even know what kind of lawyer I want to be yet, and that is in no way a sign of me not suited for law. Arts is a lot about research (writing essays etc) skills, learning concepts etc that aren't very technical in nature. This is why a lot of haters of Arts say a lot of what you learn in Arts, you can learn at home using the internet (not true, of course).
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So the end message is: yes, accept Law is hard/boring/whatever. Yes, law is competitive. And yes, everyone thinks it's easy to be famous + rich. And yes everyone wants to be a HR or Criminal lawyer (but I would think people change this thought after like 1st/2nd year). But that shouldn't be reason enough to stop you from doing it if you really want to. Why? Because if you're good enough and if you want it enough, you will succeed anyway. Stereotypes like "paperwork for your whole career" just won't cut it (no pun intended).