simple questions, complicated answers.
2) You cannot view the 'description' section on the listing generator page(whatever it is called) in either the html or standard mode on a black background, it is white. IF you want to write in white on black, type what you want, then change all the printing to white(text color). Then you can colour-highlight behind the words in black to make it easier to see(background color=text only). IF YOU have the description section as a black background in your auction template, that is the only place it will show up as black.
3)You cannot alter/change/hide the 'description line' generated by eBay.