Personally, I do not fire off the gun before disassembly. I have not seen any evidence that it helps. It also makes the gun harder to re-assemble as you have to cock the locks and ejectors as you do so, or before you can.
Also, I do not store guns in the case. The case is intended for transportation, not long-term storage.
The case lining can hold damp, which will rust the metal over time.
I store guns muzzle-down in a gun safe, all together. Fire off the locks with snap caps if you like and leave them in.
