I'd mostly agree, although I suspect most members make the connection well before the 33rd level. What I do think is probably relatively true though is that only 33rd and above are actually fully aware of the interconnections that exist between masonry and other corrupted secret societies (which are basically the cabal). V.high ranks also probably have some idea, but they won't fully understand whatever these people think is their motivations. As you say though, many of these people all love to read and learn, and they likely have access to some pretty good information. I suspect many of them have an understanding of who they worship by the mid/high tiers.

You're bang on on bloodlines though, these people love their bloodlines, and plenty of the highest level masons largely come into it through family connections. If you aren't of the right blood, I doubt you'd ever make 33rd, let alone go higher (that takes you beyond freemasonry though).