organised religion is mostly about power and culture, tom. the definition of fundies is that they take whatever's written in the "holy book" (bible, koran, torah, etc.) as the literal truth, which must not be interpreted on an individual basis. so the fundies don't interpret it, but leave it to those further up the religious hierarchy to do so, and
they do so to further whatever agenda they have, generally.
they can do this because there
is one "holy book", which is, basically, dogma. and this depends on the time and the culture: if you read leviticus nowadays, it's utterly ridiculous - you'll be burning in hell cos you wear ripped clothes/eat prawns/have a wank? yeah, right - it's potty. but read it from the perspective of the times, and they were a relatively small group of people moving to another country and trying to establish a nation there. so, obviously, resources were scarce and you had to keep your clothes together, cos there wasn't going to be a shop you could pop into and replace them. shellfish in a hot country? don't bother. and they were trying to build up the numbers, so having a wank wasted a potential child, etc. make sense?
but we're not nomadic, and we don't need to up the population, so it all sounds like utter mince now. and that's where fundies have a problem, cos they still want to take everything literally.
a lot of what you ask is about interpretation. when i was a catholic, i decided not to accept any "given" interpretation without questioning the whole shebang - my poor priest tried to field my constant philosophical debates, but he just wasn't up to the theological minutiae i wanted. so yes, i did pick and choose the bits i fancied, if you like.
and that's why my spirituality/path/way of life (i prefer the latter) doesn't involve dogma, or a holy book, or interpretation: i'm more interested in issues/right and wrong/ways of working in the world, much the same as my politics, which are issue-based rather than party-based.
any of that answer any of your questions? or even make sense?