You should definitely contact the PD and probably also set up a meeting with him/her. It will demonstrate your interest, and it will remind the PD to ask the residents and attendings how you are doing while your performance is still fresh in everyone's mind. Meeting with the PD will be kind of like an informal interview, and it will also be an opportunity for you to become a real person in the PD's eyes rather than just a name on a file, and to get some more of your questions answered about the program.
Many PD's expect that all visiting students should meet with them during their time at the institution. At the program I trained at, we told all our visiting students to specifically make an appointment with the PD during their rotation because the PD expected it and he valued the opportunity to meet with interested students outside of the busy interview season. You can ask the residents you are working with what the expectations are of their PD (I'm assuming they already know of your interest in the program)
You should also contact the PD before the end of your rotation, to give you some time to set up a meeting if he/she wants to talk with you.
