Shoutbox

There is a script that can do part of what you requested. It is called "Auto Hey". It replies with "Hey" whenever the other person says "Hi" or similar. I am sure that this could be modified to respond to other messages, like "How are you?". The second bit of your suggestion would be much harder. You would need to detect what had been said on a per-chat basis, not for the whole program.

Hope that this helps,

Robert