Hi
rear parking sensors, either a bad sensor or a dodgy module, especially if the boot gets damp
petrol gauge may be a dodgy fuel level sender, theres one each side, check the connections, just needs the back seat lifting, you can put the dash on these in diagnostic mode to test all the gauges on the dash
performance would start with a good service and go from there, rear plugs are under the plenum, so they dont always get changed,
sport mode can be down to how it ws driven previously, if left in sport mode when driving slow it adapts to that driving style, in sport it raises shift points and should drop a few gear when floored and go all the way to the red before changing gear, if it working right. Again a good service works wonders, some people avoid as service part for the zf 6hp26 not cheap, avoid cheaper pattern kits, they always leak and cheap oil causes all sorts of problems.
cloudy headlights get your self a 3m headlight restore kit off ebay, about 25 quid, will bring them back to new, all you need is a drill and some masking tape to protect the paintwork
if you need any workshop or electrical manuals look here http://www.jagrepair.com/
cheers
Joe