customer service improvements because of live chat?

Hi there,

I posted this in the Ticketing Forum but maybe it belongs in the Customer Service forum...

Do any of you offer a live chat feature on your website?  If so, would you mind answering a few questions:

1) Where is the option presented? On problematic transactional pages, login page, a permanent menu item, etc?

2) How many chats per day do you handle?

3) What are the hours of operation? 

4) Has having live chat cut down on the number of calls from frustrated or confused web patrons?

Any other helpful hints or lessons learned?

Thanks!
Mary