Real time - Which is the best way?

I think that I'll use socket.io or something else with nodejs, because my project never will be like facebook ahah! I'm obsessed with how facebook manages all requests (json, script js etc).

However I coded some months ago a real time chat with socket.io all by myself but I had some issues, I write them here, maybe you can give me some idea:

1) we have two users, A and B. They connect on a private room only for them, when A send message he sees the message with the message sent by him, and the user B see the message as if received, but if user A open 2 tabs on browser, in one of them he sees the message that he sends as from another user, I think it was a mistake about the session/token (?);

2) Is possible to emit some message to an "array" of user? Instead: A make a post; B and C comment its; then D comments the post -> A, B, C receive the notification about D. Is it possible?

Sorry for my english, I wish that is correct.. ahah! And sorry also for this question, thank you for all your help, specially to albertleao !