Arghhhhhh, Sorry to have gone to sleep last night!
You are very very lucky with the brass and metal polish, normally it effects the anodised surface. (certainly does on ATCS cases)
Those dirt marks are very nasty but familiar, i had a 201 that was covered in a similar black powder, was kind of like soot dust. Have a look inside your box and see if there is any of this powder on the inside of the box.
Baby oil is something else thats supposed to do wonders with anodised alu with regard to finger marks, butnot sure how it would cope with those dirt marks!