From your handle I thought you were Japanese? If you're going for a tourist visit you shouldn't need one. (Keep in mind I don't know what they did in the Homeland Security Dept since I've been away.) I thought the US and Japan had a mutual agreement that we could go between countries with a 90 day visa for tourist purposes. At least, I've always been given a landing permit without worrying over visas. (But, I'm American going to Japan. But I swear I thought I saw something stating free movement.)
If you're going for long term business, then I can see them wanting the above information. The gov't fears people will go in without means of supporting themselves and become a burden on society. I believe that's the official explanation, more or less.
If it makes you feel any better, I had to jump though lots of hoops when I came to China and got married. And that's a yearly set of hoops to boot!
As for questions, if it's anything like China, they'll ask your purpose in going, when/if you plan to return to your home country, and stuff like that. Just be yourself, and for goodness sake, if they ask you whether you're planning on returning to your home country, say yes. (Unless you're immigrating to the US, then can't help you.