#2
Amplitube=Metal tone
Guitar Rig=Rock tones and effects.

And not really. Amplitube is prolly the closest to a really sounding amp!
#3
so if i conect a guitar plug with a normal headphone end into my pc, my sound card wont blow up right?
#4
no, but you'll have hella latency and it'll sound like crap depending on your sound card.
#6
USB interface. stuff like the toneport or fast track usb.