I can say new search is too fast. I have no idea when it does indexing but at the very first boot, I could find a lot of things when I just put a word.
I guess New search does not use some kind of indexing but PDFs.
Isn't there a DB for storing file names and kind in hard drive?
It might be mixed up those stuffs.
Spotlight is developed for applications which use spotlight development kit like new System preference.
If developers make some apps like that, the apps can use spotlight technology.
Think about Web kit. Since WWDC 2003, anybody can make a web browser without coding by using web kit.