I have a set of old samples in the form of raw wav files, with multiple notes played in each wav file. I need to turn them into halion libraries, what do I have to do to chop them up, process them (filter out the distracting ambient noises) and map them into Halion? They are old samples so no velocity layering is possible.

What do you mean multiple notes in each wav? Are they chords? Pretty sure there's no way to clean that up.