Hi there,
I have a 90 ies beosystem 7000 which has a more 'polished' metal look it than the original finish of the CX's.
To answer your original questions :
1) all the CX are anodized, but the alu finished ones only seem to have some sort of dulling protective coating to them>
2) Off course sanding or whatever action you do to the finish will change their appearance. Use wet sanding only and preferabley 600+ gritt.
3) I have now 5 polished CX100's in use as a home theater and I have done some for a friend of mine who has a beocenter 9300 with the chrome like panels on them ...... stunning combo ...
4) I used belt sanders to retain some direction to the sanding process and standard orbital polishers to full gloss appearance.
However, if the damage is limited and mainly in the paint finish (mine were beyond a paint job ....) just try to paint remover to strip back to metal and repaint... much simpler