when i created a 16 step beat and want to extend it to 64 steps, then i just hit shift and the steps selector (the double arows showing left and right under the stepsequencer) and it autimaticaly copys the whole 16 step beat to the other 48 steps. im on Spark CDM btw...
a nice feature for future version would be a sampler to live record other hardware or vocals or whatever, so you can just work with the spark 2 software and nothing else. sure VST support would be freakin awesome, but im sure this will never happen ^^