A Visit From Nemesis

I have several questions, all related to yesterday's post, in which I perhaps a smidge too happy about the ease with which Haloscan installed. To wit:

1. Where did my old comments go?
2. Why does the blasted thing not display the accurate number of comments?
3. What is trackback and why would I want it? (this is mostly rhetorical - I vaguely know what it is and don't particularly see the point)
4. If I got this.... thing for the sake of easy access to commenters' email addresses, so I could actually reply to those peoeple who don't have blogs of their own and reply to people with blogs without having to go through 17 steps to do so, why on earth can I not access email addresses of commenters? I know I can't, because I did a test with my own name. I can find my webpage, I can make a link to the comment, I can freakin' trackback, but the reason I got this magical add-on? Nope. Can't find it.
5. Did you know it's possible, after an extended period of time with very mild migraines, to completely forget the spectacularly destructive power of a real migraine? Ok, so that was only tangentially related to yesterday's post, but in between the incapacitating nausea, the avoiding of light (all blinding) and sound (all deafening), the way words do a whirling jig on the page/monitor and general whimpering, I find it fascinating that I've forgotten what this feels like, to the point where I briefly considered an aneurysm before I clued in.

If you have any helpful hints on the Haloscan issue, please feel free to comment. I'll keep checking obsessively, even though the lying pie... thing claims there is only one comment.