1: my m-audio usb keyboard works just fine with renoise… see if your midi keyboard is selected under midi input (edit -> preferences -> MIDI -> in device A)
2: what use will any audio application make without a soundcard? or did you mean some special soundcard? if so then no, renoise runs also just fine with ordinary onboard soundcard…
3: dig the internet, there are tons of samples out there. We also have this sticky thread so you can check there…