I've found that responding to comments is a bit of an art, Virginia. If the host replies too quickly, then other conversation may be stifled. Quite often I will let a comment sit for a while and see if anyone else wants to add to the thread. I also find that some comments don't need a reply, so a standard "thanks for commenting" response seems a bit contrived from my perspective.

With my current WP configuration, all posts for the past 5 years are open for further comment and I can see these on my "dashboard", so I'm not sure about the moderation function of Blogger.