To Other Bloggers...Help!

Alright fellow bloggers, I've been doing this for nearly four years, but there are still so many questions I have unanswered!  (Or really, just two at the moment.)  And since you're probably my best resource, these questions are for you! 

1) When I comment on other blogs, the blogger will sometimes respond to me via email.  However, when I try to do the same, I don't know whether or not the commenter receives my response.  I've responded with questions, yet never seem to hear back, so I'm thinking no?  Is that something on my end, or theirs?  How do I fix it?

2) Is there a way to change blog settings so that if I just reply to their comment on the blog post, they are notified?  And vice versa when I comment on others' blogs?

If you can help, I'll be very grateful!  Thanks, friends!