I just installed OS X 10.11 to check it out, as it happens I also have an Exchange account on my machine. I am able to send and receive emails from the account.
I don't have the calendar turned on I'm afraid, so I can't help you with that part of your question. But since Mail is able to connect with the Exchange Server I wouldn't expect to have any issues there either.
There is nothing in the release notes that would suggest an issue with Exchange Accounts.