Maximizing my PX-310 for classical use

[Priviamania]

I think I read somewhere that you can adjust most any aspect of a given sound on it, but can't lay hands on how to. For instance:

 

---The harpsichord sound is beautiful but the built-in effect of slightly flattening of the pitch while you hold it (no doubt in imitation of the real thing) is too pronounced. Can this be changed? If it's a choice between that or a totally straight sound, I'd take the latter. 

---The string vibrato (heterodyne, whatever you want to call it) begins after you've held a note or chord briefly. Can I doctor fix it so the vibrato starts right away? 

---The harp sound is lovely in a low range, but laughable above about middle E. Would this take replacing it with a patch from somewhere else, would this even be possible -- etc?