Welcome to the PD150 gang buddy - you made a good choice!
I have a late (August) 02 plate car in which I have already covered 45k miles. I have had no problems with stone chips at all, (still don't have one!) although I know others have - I have a theory that this comes down to the colour of the car (mine is black), as I believe some colours are easier damaged than others.
Personally, I've never seen the logic behind these car-bra things - What's the point of immaculate paint-work if its hidden under a load of plastic? Without it, the worse case scenario is your bonnet needs a re-sparay when you come to sell it, but that ?200 has gotta be worth having a nice shiny bonnet on display!! The plastic things that sit on the leading edge of the bonnet just deflect the stones up, straight up into the direction of the windsreen!!!
The fuel of choice for any oil-burner out there at the moment is BP's ultimate diesel. It costs a couple of pence more per litre than regular stuff, but there are both performance and economy benefits there, which is a win, win situation!
Sorry I can't offer any viewon your first point, I had no idea there was a known leaking rear wash/wipe. I have yet to experience any problems with this, so I'm hoping the same as you, that this has been fixed!!!