Re the front window tints, as others have already said, any tint forward of the B pillar (over the allowed 30% tint or 70% light transmission) is illegal. If you do tint them, you risk a minimum of 3 points and £60 fine (for each pane of glass), and you will invalidate your insurance - sorry, but IMHO, just not worth the risk, no matter how cool they may look.
As steathwolf stated, factory fitted cruise will get you the full three years pan-european warranty - whereas any retro fit or dealer fit and you will only get 2 years on the parts, and a UK-only 1 year warranty on the labour - and as I've personally found out to my disgust, Volkswagen UK dealer labour warranty is fcuking useless!