Is the chat still timing out? Cometchat said last night that this had been fixed. Please let me know.
For private chats with people, here's how you do it. If you are in a chatroom, you click on their username on the right, then "Private chat". Outside of the chatroom, you click on "Who's Online", click on the user's name, and a private chat window will pop up. Much like with the previous chat, it's up to the other person to acknowledge the private chat and respond.
For the background color, that's something we'll need to tweak as we move along. I was in there speaking to the users about it recently. I was thinking a lighter blue like you see in the thread posts.