About comment history, it seems that it existed but got removed (why, I have no idea EDIT: kevin_thibedeau makes a good point on that topic): https://www.youtube.com/watch?v=fcH9VR96Z1M

As for receiving a reply, I know that you get a notification, at least if people use your +name in their comment, but it isn't easy to manage given the lack of history, as you pointed out.