1. That's right. 2. That's spot on. 3. You've hit the nail on the head. / You've nailed it. 4. I suppose so. (use this when you agree, but you are not completely convinced) 5. I'm afraid you're right. (use this in response to bad news, to say the bad news is correct)
It is better to choose than to be chosen. Tell the interviewer why you are interested in the company and job opportunity. Ask them for a business card and follow it up by sending a thankyou email or letter, saying how much you enjoyed meeting them and how interested you are. Take the opportunity to detail the key advantages you bring.