Bill, the answer to you second question is that the safety will not return to safe when the gun is opened after firing. The safety slide has been removed so that the spur lever can rise up after the first firing. On Featherweight frames some of the underside of the top tang has been removed to allow this spur lever to travel far enough. And yes the stock has to come off to do any work on the safety, but in this case it does not have to come off.
The answer to your first question is I am not sure if the safety has to be on or off. Once it is selected I leave it there. If as you stated, the safety had to be on to select it, then select it and leave it there.
Funny story, a friend bought a beautiful 16 gauge Specialty with a HOT and ejectors, we went sporting clays shooting and every once in a while he only fired one barrel. I asked him if there was a problem with the gun not going off and he said no, I forgot to slide the switch. I told him there was no need to, just put the selector on the right barrel, fire and just pull the trigger again for the other barrel. This was his first HOT gun. I know I could not slide the selector with the gun mounted that fast.