I would say go for science stream.

You will still be able to catch up in your tertiary education if you decide to go for arts later.

1) Subjects doesn't matter. For me, I took science stream for the sake of general knowledge. I get to know the surface of everything, from Newton's law to body parts to NaOH. I've forgotten most of it but at least I know they exist.

2) Since you will be able to change to arts later on in your tertiary education, the prospect is infinite. But an arts student will find it difficult to change since science subjects are generally more difficult.

3) It depends on what you want to learn in the end. Some went pure science, some did not take up Biology, etc as some find these subjects harder to comprehend.