My plan this year is to focus on building a sizeable portfolio of stocks.

Because I am based overseas, I need to use a stockbroker that poses minimal risk, but at the same time not charge exhorbitant fees for commission.

My question is this: What are the pros and cons of using a major stockbroker versus using a smaller (lesser known) firm?

Any views would be appreciated.

Most large stockbrokers operate nationwide, since they are affiliated with their parent banks e.g. FCMB, GT Bank, IBTC.
There are other smaller firms of Brokers, typically found in Lagos Island.

Are these firms safe to use?
Is my money lodged in their account at any point in time? Or is it lodged directly with NSE?
Is my money lodged with them at all times, hence why they can trade on my behalf?
What happens if they go out of business?