moggy lover,
The question was about dogmatics -- what Christian churches currently teach about "hell" -- not Biblical theology about she'ol, hades or gehenna.
Even for a Bible believer there may be some delusion in dealing with Bible expressions relating to she'ol as (revealed) "information," considering the obvious continuity with other ancient Near Eastern representations of death and the netherworld (same with hadès or tartaros and Greek mythology). Plus, there is no clear border between "realistic" mythology and poetry, and what you retain as "data" is somewhat arbitrary. If the "gates" or she'ol are "literal," why not its "mouth" (Isaiah 5:14)?
You are right in pointing out that most NT references to gehenna are eschatological. Otoh the kind and weight of eschatology have varied greatly, both in Judaism and in Christianity. As short-term futuristic expectations vanish, the resurrection and final judgement tend to become irrelevant technicalities, the real issue being what will happen to the individual at death. The more the intermediate state looks like "heaven" or "hell," the less meaningful is the final judgement and the shift to a final state.
About the rephaim you might enjoy the following thread http://www.jehovahs-witness.com/10/68224/1.ashx