1st question...ATA66. Basically harddrives that are ATA66 can transfer 66MB/sec. ATA100 and ATA133 exist too (100MB/sec and 133MB/sec). ATA33 is an older standard, and then they get slower from there. However, I'm not really sure that tweak does anything... I left it in there just in case it does (certainly doesn't do any damage) but I've read some stuff that seems to indicate it doesn't matter.
2nd qusetion...here and there and everywhere. I picked up some of it at work from friends. Picked up some stuff from a tweaks mailing list I'm subscribed to. Picked up other stuff from various websites. I kinda combined everything I learned/knew and did a bit of research on it, then put it up on the page. Original reason was that my work had us on Pentium 133s with 32MB of RAM, running win95.
Horrible, horribly slow. Especially since we were basically required to have 1 application and three browser windows open at all times. So, I tweaked the crap outta my system to try to get it to work a bit better.
There, nice, long answers.