#1
I understand regular tabs and Guitar Pro tabs perfectly fine but I have a little hard time understanding this one:
http://www.musicradar.com/tuition/guitars/wes-borland-on-two-handed-tapping-34947
The tab is here:
http://cdn.mos.musicradar.com/images/Total%20Guitar/Issue%20150/WesBorlandTab.jpg

I know how to do this technique.
What are the rings and squares? Is one bar one riff? A and i?
Dissonance is underrated.
#2
For your picking hand, "a" would mean your ring finger, "i" your index finger.
p = pulgar (thumb)
i = index
m = mayor (major/middle)
a = anular (ring)
c or e = pinky (not sure on the Italian here)

Squares for fretting hand, circles for picking hand (all of these using the tapping technique). If you're a right handed guitarist, then squares are your left hand, circles are your right hand.

The dagger (or cross) indicated on the staff is explained on the footnote.