Repeat step 4 and 5.
Avoid quickly movements or weight dropping.
Doing bench press with Smith machine it's not a natural movement path of the bar. At the first signs of discomfort in the shoulders, stop the exercise, as the movement trajectory of the Smith machine may be potentially dangerous. Try to adjust the seat and see if it makes a difference.
Do not touch your chest with the bar. This causes unneeded stress on your shoulder joints and takes the tension away from your chest muscles
Stablizers muscles are vitally important. As you are not working or strengthening your stabilization muscles, your muscles progresses unevenly, what may cause body disbalances and injuries. The best suggestion is to mix this exercise with other chest exercises, like Dumbbells Bench Press or Barbell Bench Press to receive the best from all the worlds. Ideally, this modification will make sure you develop in all directions and not just bulking up.