Stephen LaBerge is the man who scientifically validated LDing, and still is the leading researcher on it. Any books by him, like the one suggested by EternalStarshine, are good references.
As for the B6, it really does help dreams a lot. A single banana probably isn't enough for a noticeable difference. Try taking 50-100 mg (but not any more than that, ever) a half hour before bed. It'll make your dreams amazingly vivid.
As for general lucid clarity, it varies. I've had dreams where things were so blurry it looked like I was in the original DOOM game. On the other hand, most of my lucids are so clear that I can see details several times smaller than what I can see in real life. It just depends on the level of lucidity and your skill at LDing. The more you work at LDing, the better it gets.