Is it possible to trigger sample slices (09xx) by assigning them to buttons on midi controller? Or somehow link it to the key-tracking device, so that when I press different keys, it plays different slices?
no, not right now, but it’s highly anticipated… at least by me 
Check out:
Use Midi Knob To Set Loop Markers.
Use Midi Switches To Change Loop Markers
Setting loop points is sort of a slice of a sample. Not exactly what you are looking for, but cool anyways.