Reviews are very much read -- if not by the author, then by others looking over stories. And honestly, I don't think there are many people who would put the effort into writing a story to publish for free and not care about response. If they didn't, they wouldn't put it up. Also, an email is sent to authors every time there's a review...so it is DEFINITELY noticed.

I hear the issue with the top ranking...but I think the idea is, is it ready for publication ie, is it polished, perfect, nothing at all could be improved. At least, that's how I treat it, but then I give out very, very few 10s.

As for further exchange, the author can always respond to comments and it's up to the reviewer if they ever want to come back and say anything more.