Couple pointers:
1. You're starting your 4th year and just meeting the chair and PD? You're a bit behind on networking. You need to get engaged and stay engaged with each closely through your upcoming sub-i and especially after (i.e. you do not want to just do your sub-i then disappear). Your chair will be writing one of your letters and can be a HUGE advocate for you during the application process. The PD drives the majority of rank list discussion at some programs. When it comes time to rank students, you want them to know just enough about you. You want to be a known, desired commodity to the department. But you don't want to be so known they can see all your warts.
2. Have your CV polished and with you. Don't come in and say "Hi, I'm so and so, here's my CV." But have it with you in case they ask (they should if you're talking about your application.) Meetings are generally pretty informal, but you never want to be too comfortable around your potential future employers. Try to be personable (i.e. be yourself) and don't be nervous - they aren't going to grill you. They want to help you. Have a few questions prepared ahead of time, but only a few. If you have more questions spread them out over several meetings, several months, etc. You want to appear interested and interesting, not needy or annoying. Shoot for a meeting length of around 30 minutes.
3. When you meet with the chair, do NOT say "what are my chances?" This makes you appear like you doubt your abilities or are wishy washy about your specialty choice. It is better to approach the conversation such as: "I am 100% committed to otolaryngology. I would rather fail to match into otolaryngology than apply into any other specialty. That being said, can you look over my CV with me and talk with me about how I can best maximize my chances of matching? What are my weaknesses and how can I best remedy these between now and September?" Do this with both the chair and the PD. The chair generally has a better sense of the strength of leadership of other programs. The PD generally has a better sense of the nitty gritty of the application process from the perspective of the program side.
4. Be prepared to answer the usual questions e.g. "Why otolaryngology? Tell me about yourself. What is your 10 year plan?" Have earnest responses beyond the usual contrived responses (e.g. "love surgery and love the anatomy"). If you have research experience, be prepared to talk about it. Be prepared to talk about yourself. These meetings with the chair and PD are great times to polish questions you will be answering on the interview trail.
5. Get to know the residents. They can be great sources of advice during application season for the little "stupid questions" you wouldn't bother your chair or PD with and they are often closer to the grapevine about scuttlebutt about certain programs. They are the best source of perspective for applying from the applicant's perspective. They can be advocates for you during ranking.
