Commerce

Yes, it's enough. If you are interested, you can go for higher studies.

Yes, it is compulsory to get passing marks in maths. But it's not compulsory to add it in your best four percentage.

Yes, you can be an upper primary teacher.

Yes, it is possible but you have to do hard work because after two years you have to face maths which will be difficult for you.

Better ask him what is he interested in than asking about good stream. Stream he is interested in will make him better else drain him. Most of all upto 12th, we don't learn things that corporate world needs and even that would not be taught in college till first two year. Journey till 12th and after 12th is all together different, so whatever you choose, he need to make it. So, whatever stream he is interested in will make him better.

It is clearly mentioned in the guidelines of Delhi University that you can't opt for economics (Hons) if you haven't studied maths till 12th. You can't opt B.Com (Hons) too but you can go for B.Com programme.