If you're super-popular, and can't possibly respond to all, then you can do what you damn well please anyway, but the classiest bloggers at least put a general note saying thanks for all the comments, or respond to a few here and there.
3. If you have your comments option on, unless you have more comments than you can handle, leave your "receive your comments via e-mail" option on as well.
I've heard people say "I didnt' know you commented until my friend told me" or "Sorry. I hadn't checked my blog in awhile." What's up with that? When it comes to your own blog, who wants to be the last to know?
4. The best way to generate comments is to visit other blogs and comment to them, and link to them too if you think they're good. Basic good karma/golden rule/blogger etiquette stuff.
Well, that's all I can think of right now. I hope people will feel free to comment about my comments about (mostly) comments — if so, I promise I will try my best to comment back.