using a 5 step approach...I feel like my last step is very long and I over stride. I also have a bad habit of finishing heel\toe (planting rather than sliding). Any good drills to practice to get the length of the last step back down a little more compact to allow better balance?

Really would like to eliminate the planting on the last step but have done it for so many years not sure that will every go away completely.

Walk up the the foul line.  Turn around facing the bowlers area and put the heels of your feet a couple inches from the foul line.  Take 5 regular walking steps back towards the bowlers area.  Add another half step and turn back around facing the pins.  This should be your starting position.  A lot of people when they bowl tend to take longer strides than their normal walking stride.  Unless you are taking really short steps towards the foul line when you are bowling; what I just suggested should be able to make your steps "normal" and prevent you from over striding on the last step.