HB,
Welcome to the board. Thanks for taking such a wholehearted interest in protecting your friend from going down a very destructive road.
Before I comment on the illogical reasoning of the Dubs, the great boasting sessions probably refers to District Conventions (annual) and International Conventions (every once in awhile, not regularly scheduled). I was a Dub for many years and that seems to be the context in which the other posters use the term.
In any event, you've hit the nail on the head by asking if the Dubs think this stuff through. And, clearly the answer is, "NO!"
It is such a bizarre set of beliefs that denies the reality of the geologic record and the length of time that life has been on the earth. According to the Dubs, each of the creative days in Genesis is 7, 000 years long, and since God didn't start creating life until the 3rd creative day, that means that all life on earth is only 28,000 years old. If you want to read a fascinating and thorough dissection of the Dubs' beliefs about science and evolution, there is a link on Freeminds to Alan Fuerbach's (sp?) commentary.
As far as I am concerned evolution and the history of life on earth is the bottom tier card in the Dubs' house of cards of doctrines and beliefs. It is fairly incontrovertilble that evolution delivered us to this point in time. The Dubs belief in special human creation, the fall from perfection into sin, the need for a savior/messiah to redeem humans, the belief that the earth will be restored to its original perfect state, and that humans will live forever...simply collapses under the scrutiny of critical analysis.
In spite of the occasional intelligent person who gets sucked into the Borg, it is no accident that the Dubs prey on those who are less educated, poor, living in despair, or in some other way beaten down by the world. The message is naturally appealing to those who need to latch onto some way out of their dissatisfying lives.
There is a lot more I could say, but it sounds like you are digging up plenty on your own. No doubt other posters will have their own take on things to share with you.
Cheers,
Alex