+1 to Ian's question.

In addition, coming from a background as a trad piano player who relies on the sustain pedal for sustaining notes, and simply using key pressure to affect volume , I'd like to know how to orchestrate these features together, especially for sounds (voices) that respond to either key pressure and/or volume pedal such as strings and sax. When do you call on the 'volume pedal' vs 'key pressure velocity', to augment, or takeover the task of increasing/decreasing volume?