Not sure if these are dumb questions or not........but here goes.

What firearms if any is it safe for the firing mechanism to be fired on an empty chamber? You know........when you hand over your pet rifle and the guy wants to feel the trigger pull etc.
Is it better to have an empty hull on hand to slip into the chamber for this?

Also should a rifle/shotgun/inline be stored with the gun cocked or fired? Does it really matter.