Steps 12-15 seem to be not necessary for battery replacement. They are not required to remove and replace the battery and they at least DOUBLE the amount of work. Most of the time spent on this process involved working with those tiny screws and maneuvering them in place and screwing them down. Steps 12-15 are three of the five screws that you work with inside.
Also, there should be a note at the beginning of Step 2 that if you bought the iFixit kit that you should go directly to Step 6.