Getting full mobility in your wrist extensor is important because it allows your wrists to move properly in the backswing so you do not have an open face at the top of your backswing
This one, two, three Rhythm Drill is great for perfecting your tempo, just even out the timing, and allow your swing to flow with the count
If you lose your balance during the swing then you probably made a bad swing, make sure your body is balanced on your front side at the end of each swing