I only read the Da Vinci code, so I can't discuss those views, but I see Dan Brown as a pulp fiction writer, nothing more. I find his allusions that his stories have more to them than simple fiction a distasteful sensationalist way of promotion.
If you have a mind set on conspiracies, read Umberto Eco's Foucault Pendulum, it's a slap on the wrist for all conspiracy-theorists out there. And it's a pretty good read too.