Stev,
1. No I just sanded down the walnut surface a little until I had got through the lacquer so it was rough enough.
2. No I didn't, maybe I should have but the finish I achieved looks OK, it is a bit rough but I was worried about discolouring the paint by putting lacquer on it.
3. It does scratch easily, don't take your stereo out without removing these painted parts as you will knock them, I have done it twice now!! You can clean them really eaily and sometimes when I have the time I give them a recoat to try and improve the finish?
I painted them the same colour as the car, so it looks OK.
Hope that these answers help.