1. Yes
2. Genetic loss is I believe the most common form of deafness at birth, other later causes can include oxotoxic drugs, exposure to loud sounds, head trauma, or genetics again.
3. Severe-Profound
4. No idea
5. Yes
6. Not that well, but it depends on the person. Some people sound like they have a heavy accent and talk slowly, others might be very difficult to understand.
Anyways, unless you actually know the Deaf community you're going to have a very hard time writing a book that isn't lauded by Deaf people. Too many people in my English class decide to write a story about being deaf anytime we read of Mice and Men (3rd time now) and they just write the most comically audist stories I've ever heard.
