Ultimately, you should aim for the CFA designation if you would like to be a securities analyst. The CFA helps you become much more mobile over time. It's hard to define what makes a good trader. A good understanding of the market, quick reactions, analytical skills and the ability to bluff help. Read Liars Poker by Michael Lewis to learn more about sales and trading.
Most large firms operate out of New York.
Even if you are interested in working in another location, your general interviewing activities are likely to be centered there. Other places you should look at include Hong Kong, Tokyo, London, Moscow and Singapore. If you go looking for a job in investment banking using informational interviews it is crucial that you make several trips to New York. A crucial success factor in investment banking is teamwork. Being able to pull together persons with large egos to get a presentation together for a client is a challenge and is likely to be rewarded highly.