I'd like to know what's the best setup and if
it is possible to use
Linux on a laptop to replace traditional keyboards.
yes.
So the
requirements would be, zero latency
Zero is simply impossible, even on traditional instruments.
Install JACK.
linux supported audio board,
If it is a notebook try USB.
linux based sampler/sequencer
Fluidsynth/qsynth.
and STABILITY !
I think it is possible to set up a machine which is stable enough.
Best regards
ce