From what I recall there are specific mudguards for the Defy, it would probably be easiest to go for those. Crud Roadracers or SKS Raceblades would most likely work fine with the clearances involved.
As for lights, I have a Cateye TL-LD610 attached to the back of my rack, and a Blackburn Mars 3.0 attached to my backpack. On the front I have a Cateye HL-EL135 just to help oncoming vehicles see me. It's not bright enough to light the road, but it's small and the battery lasts ages. If I'm going to cycle in the lanes in the dark, I attach one of my torches (usually a Fenix LD20) to the handlebar, so that I can see where I'm going. I doubt it's anywhere near as bright as the setup Jonny ///M has, though!