Qtn: Is your live help available 24/7, there's always someone manning the live chat?

What is the purposes of your live help? To get feedback or answer questions? To get feedback, a simple contact form will suffice. User expectation of live help is Instant Resolution, if you can't provide that level of service, there is really not point having it. Sites like tender, satisfaction will meet your needs.

Consider the cost factor of using live help for the long run too.