Yes, that is the proper procedure. However, with the safety on, you do not have to "pre cock" the hammer. I believe that is there as a drop safety, so that the hammer isn't in direct contact with the firing pin. Since the safety blocks the firing pin, you can let it all the way down. The trigger will work as DA in either case.
And yes, you can just let the hammer drop with the safety on, although i don't like to do it. I imagine it's bad for the hammer...that being said I do still do it. I dry fire a lot and I always keep the thumb safety engaged when doing so.