I have read The DaVinci Code - thought it was a great book, interesting mystery and lots of intriguing theories as well. I wouldn't say the "information" was 100% accurate, but then it is a work of fiction and it's been a long time since a book actually had me looking stuff up on the internet, as this one did! I just started Angels and Demons today - seems like it will be another good one (and yes, I know it preceded The DaVinci Code).
As for the Detective - I think BWL is referring to the French police detective who pops into the story occasionally and has a cameo appearance at the end. I didn't think he figured much into things either.