Hey there,
The way we work the tabs at Guitar Tricks is that I play and teach the song and the tabs are then generated from the lesson. So no, I don't follow the tabs, it should be the other way around ;)
As far as the slide to the 5th fret goes, it's not important which fret you start on. There are two kinds of slides: 1) where you slide from an indeterminant lower fret and 2) when you slide from a particular fret. The very beginning of the song is a good example of the latter.
I hope this helps, Tom