#2
Sounds just like regular tapping, definitely not making a sound like a pinch harmonic
Literally, take a finger from your picking hand a tap notes with it.
bear in mind there's the backing track playing alongside him so it sounds like it has an octave effect on the guitar
ohai little sig.
#3
he is tapping the note that is one octave above the note fretted. for example, if your finger is on the 5th fret in any string, you would tap on the 17th fret. you have to experiment how hard or how soft to tap to get the best sound for your guitar, because that varies on some different guitars.
#4
you get 2 awesome harmonics at the 7th and the 12th right? Well if you fret a note on the first fret and 'tap' the 8th fret bar (like a harmonic) it will ring. Extrapolate this idea.