The blood issue is because they believe the bible tells us we should only use blood in sacrifice, nothing to do with it being unclean or anything like that, they just believe god has given one purpose for it outside the body.
There are many confused and gullible people in the JW's, I've met several.
You get people bringing their own interpritation into the religion, hence the disgust at you using insulin, while other's would be fine with it.
There literature prints lies and physical impossibilities to justify some of their beliefs (like claiming the thermosphere is 3000F!)
Most that I have met joined simply because they like the idea of coming back with a perfect body, so you get a lot of couples who are infertile, and disabled people joining.
I find shouting "I'm naked and in a highly excited state. I'm opening the door in 3....2...." usually works
They don't have churches, they have "kingdom halls"
They're also quite good at excommunicating people, including their children.