There are some audio development apps available in the repositories. They even exist on iPhone OS. But I don't take any of them serious.

You won't have VST available either since most of these are written for Windows/x86-32 hence won't work on Linux/ARM.

Although, judging on your screenshots, you're not going to use synthesizers, require MIDI; you have your samples already.

What you then need is a sequencer or tracker.

A program to resample your samples. Preferably in the sequencer or tracker.

Your last screenshot is just the same as the piano roll; just a difference interface, and allowing some resampling options not available in 'piano roll'.

You're also going to need the stylus. Or some kind of zoom option. And the knobs which you turn around are not nice combined with a touchscreen.

Hate to be a negative *** but you're just better off with a netbook running Windows XP and Fruity Loops provided the sound quality it delivers is good enough (read reviews for that).