On a QS, you pull out the crown to the first stop and then turning the crown will set the date as you turn.

You'll want to set the date to yesterday's date and then pull the crown all the way out and advance the hands to either the first rotation or second rotation of the correct time, depending on whether it's AM or PM.

Then push the crown in and screw it down.

As to your second question, it's all right to let it stop every few days if you're not wearing it; a better solution is to use a watch winder to keep it wound.