What does the warning light on my dash mean?

I have a yellow warning light on my Rover 75 that shows an empty circle (no ABS inside, for example) with what looks like an open and close bracket either side. Would you know what this is for?

Is a 1998 Audi S8 going to be stupidly expensive to maintain?

I am thinking of buying a 1998 Audi S8. What are the common problems with these cars? Are they stupidly expensive to repair and maintain?

Should I remove the undertray from my Alfa Romeo Spider to prevent rust?

Do I need an undertray on my Alfa Romeo Spider. I've heard that they hold water and encourage rust?