OK... my initial reaction is probably very similar to what others said about that book back in the day. What good will this book do other than increase illegal activity? If you could somehow focus it in the direction of the white hat crowd, I think it would serve the community better. How would you do that? I'm not exactly sure. Maybe the title of the book could be something like:
"What Virus Code Can Teach Us about Efficient Programming" or
"Creative Coding the Viral Way"
or instead of Ethical Hacking, you could play on that theme:
"Ethical Virus Programming" or
"What White Hats Can Learn from Virus Code"
Just brainstorming out loud.
As for your specific questions:
1. Both. I would give specific examples but then also encourage them to continue their own research.
2. Again, I would say both. Keep in mind, that if you only do assembly, then you are limiting your audience. That may not be a concern of yours if you are in it more for the sharing of knowledge and not the money that comes with additional sales.
3. Only you can answer this one. One piece of advice. Other people don't define, but those that associate closely with define your image and how others see you. Again, this may not be a concern, but if you write a book solely on how to write a virus, then you may be inadvertantly be linking yourself with that community. If you come up with some kind of angle to move it towards the white hat side, you may find that in the end, this is how you want people to know you.
Hope that helps,
CISSP, MCSE, CSTA, Security+ SME