+1 on bolting it to the floor. Try to go on the hometown forums for recommendations on any local safe shops where you might be able to haggle on the price by a few hundred, get free shipping and/or some other free accesories.
I specifically looked for external hinges when I bought my safe, so I can swing the door open all the way without having to worry about damaging the safe. If you have a decent safe with bolts on all four sides, the external hinges don't retract from security at all. I doubt humidity will be an issue in Nevada unlike it is in the gulf coast, so I don't think a dry rod will be useful for you.
If you go with a dial lock, go with a reputable maker such as Sargent and Greenleaf (sp?). I personalliy don't mind having a slow dial lock, because I'll always have a gun handy. I've seen a few electronic locks thave give you the ability to place a 9v batttery against two terminals for emergency energization.
As for preventing heat damage inside the safe for CDs and the such, you could put them inside another insulated box within your safe. It won't make it melt proof, but it'll help.
Buy as much safe as you can, because you'll find things to stuff into it (like more guns
) Good luck!