If you left-click on the name of the person in one of their posts, you have two options- private message or email. If you contact them by private message, you're using an internale system, so they don't see your email address. If you use email, it will use the account you gave when you signed up.
We don't have any chat options here simply because we cannot monitor them all the time and it would be a security headache as we would be responsible for what goes on in the chatroom.
