I have to say that seeing all of this shuttling back and forth between different applications makes my head hurt!

And to the OP's original question - I also use Garageband for iOS on my iPhone 4S. A simply amazing application for $5 and it helps me as a scratchpad for when inspiration hits and I'm not in my 'studio'. I don't know that it's a DAW per se, but neither is BIAB. So we've all kind of expanded your definition of DAW to an overall concept-to-finished-production songwriting/recording/print to digital audio process!