i want to play this kind of music with my guitar: http://www.youtube.com/watch?v=57ULavCtBtc

should I get acoustic or electric? Thanks

Sounds like that's being played on an acoustic guitar, but it's likely an acoustic-electric-- an acoustic guitar with a built-in pickup, basically, so you can plug it in. Consider one of these.

are they using picks or no? or fingering?

They're using picks.

I would also say they're using acoustic-electrics because the sound is very bright, so sounds like there's some EQ'ing going on either on-board or in the mix.