On a MIDI controller, do you need the computer there with you? Or does it load it all on the board?

Is there alot of customization you can do with the sounds on a synth? Or does it vary per synth model itself?

Another guy told me that this: http://www.sonicstate.com/synth/_inc/picview.cfm?synthid=530
Used might fit my needs as well. Hows that compared to the QS 6.2

Thanks,
Stevo