hard to answer the last question. Simply, there are 1000s of brokers already and all work differently. I can not say really about your case, but as Jacpin says, you should keep an eye on it always, and have in mind that the brokers benefit when we lose(forget the thing they benefit only the spread)
Now I have worked before for couple of brokers, and they really work differently. But most of the time there is the old A book and B book. In A book are the people who profit, and there are different way to manipulate the accounts to lower the profits in these account. And this is most of the time with manual trading. And that is one of the main reasons why I the recent years I have started more algorithmic trading. There is not too much there to be done from the brokers. As said most of the people working there have no idea about Expert Advisors, which gives as some security.