#3
It's a strum using the individual digits rather than the whole hand as a 'clump' or a plectrum
It helps to get a rapid succession of strums.
As to making it more interesting... I have no idea sorry.
Ibanez S520
Yamaha Pacifica 112 with JB.Jr Neck pickup
Ibanez Custom Blazer
Peavey Bandit 112, Marshall Valvestate 20
Marshall Jackhammer, Zoom 505 effects, Boss ME-50
Boss Pw 10 V Wah
Dunlop 1.5mm Picks, D'addario standard Strings
#4
look up "guitarra flamenca" on youtube... there are some pretty interesting exercises...

edit: "bulerias" might also bring up something interesting
#5
Jesus, that **** is the **** :O

Just go for a latina chord progression Am, G, F, E with barre of course and mute the strings accordingly with the fretting hand to get more rhythm into it? Worked for me :|