You are at almost last stage of admission so you need not get over anxious or over confident too.
Simple responses in suave manner with ever smiling natural face will get you through PI. With this positively you are conveying that you have ‘can do attitude’ and you have traits of becoming a good future manager.
Besides informal greetings or gestures, maximum you will be asked questions from your academic background and whatever you have conveyed in the above tests.
Area of concern for you will remain in regard to confidence level which neither over nor low is appreciated.