Reading a book doesn't mean someone automatically takes everything in it as truth. eg I've read Frankenstein and Moby Dick as well, but are they factual accounts? No. Both stories are allegories though.
The Torah is full of allegories, stories meant to teach, not be historical facts. This isn't hard to understand.
Wrong again, there's absolutely zero factual evidence that Sodom and Gomorrah existed. Those stories were meant to teach people lessons on proper behavior.
Also, the people of Sodom's sins were that of greed and arrogance, of having plentiful bounty and not sharing with her neighbors and those in need. It's a story that was meant to teach people to be humble, kind and giving. Not "gays are bad!!!!", as you probably believe.