Hi, potential fellow schoolmate. I just got my admission into NU via First Round. My major varies from yours but I think the interviews should run almost in the similar fashion.
1. As stated from the official website, the interview will take about 45 min for Engineering and Science programs. (Social Sciences and Japan-in-Asia Cultural Studies are only 30 min) Moreover, your majors will be asked some Mathematics questions so on the scale of 1-10 for how academically the questions will be, please expect them to range about 7-8 out of 10. Most of the questions they asked in my interview are academic-related to my major. There are 4 interviewers. 2 are lecturers. 1 is the admission staff. 1 is the head of my major. So yeah, since there are 2 lecturers, expect them to be technical and nit-picking. As the interview was so academical, I ranked it as one of the hardest interviews I attended.
2. I canft answer for this one as I wasnft tested any Maths or Physics questions. My questions were Econs-related. All I can say is follow what the website says. Go to this link and watch the videos to prepare.
http://ocw.nagoya-u.jp/index.php?lang=en&mode=c&id=516&page_type=index3. Not many general questions. For my case, I was selected for the G30 scholarship, and as a mature student so they enquired about it. I was a bit upset in the interview as they are honest say that I need to take extra Maths classes, and may face difficulty to find jobs in Japan after graduation due to my age, gender and race. Nonetheless, I appreciate their honesty. I was also told to talk about my working experience (I have ten years working experience), how I won the scholarship via the previous interview, and my Japanese language proficiency.
At the beginning, they will ask you is to give a short introduction of yourself. This is corresponding to the one of the essays we wrote during the admission. (Why we pick NU) Be brief and clear in explaining and go straight to the point. If not, they will stop you and tell you to summarise. Print out the two essays you have written and spend a few days before the interview to memorise your essays. Put the two essays with you as you do the Skype interview. They will keep asking you about your essays.
4. Stay calm, do a lot of prep work beforehand and answer honestly. It can be nerve-wracking as there are four people staring at you, and they usually just give you a straight face. Most importantly, show that you are serious to study, and interested in Japan. I thought I screwed up the interview but was elated they took me in. Not trying to scare you but if you have seen the statistics NU has given about the admission rate, your major is only 5%-10%. I must say they are strict. And I would say a high possibility you will meet all these interviewers again in the campus so remember their faces and names, and give your best shot.