Another "must ask" that you should end the interview with is "What are the next steps in this process?"
You'll want to know if you'll be expected to interview with others. Is there any kind of testing involved? When will they make a decision? When do they hope to bring someone on board? Is there more information or materials you can provide to support your candidacy? Who will you hear from and when? If you don't hear, when and how should you follow up?
This ensures that you're able to manage your own expectations and it gives you a handle on the company's timeframe, so you don't leave the interview waiting and wondering.
Here's some extra advice from Tory Johnson:
It's perfectly acceptable to ask the HR manager to describe the management style of the person to whom you'd be reporting. Oftentimes the HR department has a good handle on the personality traits and work styles of the company's top managers and can share some of those preferences with candidates. This helps to ensure a good fit all around.
Towards the end of the conversation you can ask if they have any concerns about your ability to excel in this role. This is a chance for them to share with you any possible weaknesses, such as a skill you lack or a particular experience they wish you had. More importantly, it's an opportunity for you to learn quite clearly what they're thinking so you're able to address any outstanding issues directly. If you can't think quickly on the spot about how to explain how you'd overcome their hesitation, it's surely a topic for follow-up, which you should do within 24 hours. Point to examples of how you've been a quick study in the past or explain how you'll get the skills and training quickly and confidently. Perhaps you can point to comparable experiences you've had and how they relate to the challenges ahead.
Don't be shy about bringing a pad and pen to take notes during the interview. Don't allow those notes to distract from the conversation; your eyes and focus should be on the people in the room, not on your paper. But if there are key elements to jot down -- perhaps issues you want to follow up on -- you should feel comfortable taking brief notes.