If you were bisque firing some pieces along with the glaze pieces, then you were firing to cone 05, not 5.
You should not leave the lid cracked during the firing- you're just wasting electricity and you could cause the controller to get an inaccurate read. Crack it at the beginning if you want, but once it's above a few hundred degrees you're not gaining anything. In fact the top of the kiln will be colder than the rest. Leaving the top peep out will work just fine, or if you're running a vent then you shouldn't be leaving anything open because you're just spoiling the draft of the vent.