Hope the interview went well! If you haven't heard back, that doesn't mean it's bad news. Sometimes they'll tell you on the day, other times it might take a week or longer. Even when I was applying for McKinsey, after the last interview I waited about a week and a half. That made me quite nervous so I know the feeling.
In terms of how many people are hired from each school - I don't think there's actually an answer for that. MBB don't hire based on a set number of positions / roles they have available, but based on how many people are good enough to pass successfully through the interview. So that means you don't have to worry as much about competition or target numbers and can only focus on your performance.