In a business environment, most people won't want to chat just for the sake of chatting; they have too many other things to do.
As a courtesy, you should also only ask a single question in each message and acknowledge the person's answer when they do respond.
While you may spend the majority of your life on a keyboard, I'm told there's many people who don't :).
If a person has taken the time to request a live chat with you; give them your attention.
You know what it's like at a store when the person is serving you and also speaking on the phone; it's just plain rude.
Until you get to know the person better, or you see them using the same lingo, best to steer clear of it.
Just as with email communications, be very careful about the use of humor in live chat and instant messaging communications.
Pose a question, then give the other person the opportunity to respond - they may not be as fast a typist as you or may have been distracted.
Most IM and live chat applications these days will show in the status bar if the other person is typing out a response.
First impressions count, so use separate screen names for your business related contacts.
The same goes for your avatar; which is a picture/photo associated with your profile.
Not only may these people be slow to respond, but their responses may seem too brief, curt or bordering on what appears to be illiteracy!