Answers:
1. It will be pretty fun...probably not as much fun as Wii Sports, but better than any home exercise gadget.
2. It's fun for the same reason as Wii Sports - I get to do some physical activity and play a video game at the same time. I also love graphs and data, like the WiiSports fitness tests, and I think WiiFit will take that much further.
3. Yes I'll use it for exercise.
4. Like billalias says, the mistake people make is thinking that WiiFit is not as good as the gym. This is for people who simply don't go to the gym. I've never been to a gym in my life...so WiiFit is not going to make me an athelete, but it'll put me in better shape than doing no exercise at all, and I don't have to display my unimpressive physique in public.
5. The target audience is anyone who doesn't go to a gym or do other regular physical activity, but wants to be healthier/thinner. See: fad diets in women's magazines and exercise gadgets on TV. Specifically I think Nintendo should try to target the baby boomers and maybe young women (especially those who just had babies - no time for the gym, want to get back into pre-baby shape at home).
6. I don't know how many games will use the balance board. I'm hoping for a new 1080, and I bet Activision will try to put next year's Tony Hawk on it, but overall, it will probably be a small percentage. That's okay as long as Nintendo can bundle the game and the board for under $100.
