the wording on 1 is poor, 2 and 4 are redundant.
treat every gun with the the respect and care due a loaded gun.
ensuring that a gun is unloaded does not absolve you from keeping your gun from pointing at anything you don’t want to shoot, and that you keep your booger hook off the trigger until you’re ready to drop the hammer.
There's some validity to that ... if you don't know what it is, how can you decide whether or not you're willing to destroy it?