Are you guys looking for the best rates in the market when deciding to buy/sell Bitcoin or you're bond with the certain exchanges where you have an account?
If there are option that you can buy much cheaper in other exchange even i dont register there i will grab that . That was a potential earnings but before doing that you should review the exchange you want to try and check if theres negative feed back given on that exchange.
These topic is very often and common so what you're looking for is easy to find based on the experiences and opinions here. Try to explore here and the answer to your questions will follow. The opinions here are almost the same and is aiming to help you prevent losses while you perform trading.
I suggest that go deeper from this website, don't rely on what is obvious but the basics of trading will really help you to become a professional trader.