I think I am confused by your "mpc speak." I have an mpc. As far as I know a "sequence" is just a loop of tracks playing however many bars you choose. The "track" is just an individual loop...like a bass drum track...and snare track. A song on the mpc is a bunch of sequences ordered to play one after the other in whatever order you program. we may be talking about the same thing, but in different ways.

with that said, why would you program sequences to build for live work? why not just write loads of "sequences" and use the track mute option to make you sequences build or fall on the fly? granted you still gotta write loops. make sequence 1 and 2 have some of the same samples/midi so that the transition is easy, etc. MH suggested to use no more than 16 tracks per sequence so that you can see them all in the track mute screen. Make sure to write patch changes to your synths...blahblahblah.

Damn, if you got a nord, why didn't you hook it up in the first place? play it in and record the midi, then tweek like mad whilst your playing live. the mpc is all about jamming. play the M-F rather than program it...

Also, I would suggest that you not try to emulate what you have done in cubase. make a program on the mpc, hit record and start playing the pads (or midi keyboard) as you like. As one reviewed said, they are like musical sketchpads.