While I haven't done this, the biggest concern you should consider is the number of server calls that the tracking will use, and IF anyone is actually going to use it...
Also, how is the data going to be presented?
For any complex tracking, the first thing I do is try to visualize what the report is going to look like: What type of data will be presented, how will it be presented, what options are going to be available, etc... I make sure I have a clear vision, and also confirm that vision with the intended audience.
I am not sure that tracking prompts and responses and conversations, etc is a good idea... that could cross into privacy concerns... so you might also want to check with your legal department about collecting such information. Maybe it would be better to try and collect more general information like the topic? This might also make the report easier to read (rather than a million different prompts, it would be a limited list of topics related to your site?)
It certainly is an interesting challenge, but not knowing your site, your server call situation, and what your business needs, I can only make some generic suggestions.
