How to become a analyst at BB if I’m from Ireland

I am from Ireland and am 15. I am in transition year (4th year). I have always been interested in Private equity, hedge funds and investment banking. I am very athletic and do well in sports and school. I have a few questions regarding Becoming an investment banker in either New York or London (will most likely have more opportunities in London because im from Ireland). 1. Should I do a complicated college course like economics and finance instead of something relatively simples like commerce? 2. What other things should I do to give myself a better chance of being an investment banker (especially now since I have more free time as I am in transition year)? 3. Do I have a good chance of becoming an investment banker, despite going to a public school( I get good grades anyway)? 4. Please again tell me some things I can do to increase my chances of being an investment banker