Its free at www.absolute-chaos.com good people there and many ep members are coming by :)
First off ye click on the Yahoo! Messenger chat icon on your desktop... and of course exchange the handles or nick with the one(s) you are wanting to chat with.
Oh, Within EP?? See above unless ya want to waste money for a paid chat app.
you write stuff, they write stuff. when the stuff they write relates to what you wrote and so forth, it's called a conversation. also known as chit chat or chat for short
If you pay for it, or are a supporter, or volunteer (ie, pay ep) you can use it.