From what I have been able to understand (so subject to correction by any medical people):-
1) a few weeks, like any 'flu'
2) unlikely, due to the shipping transit time (if by sea), during which the virus would dry out completely and become non-functional.
3) No, but it is quite a likely possibility. What I don't know is what degree of virulence it will have by then. These viruses change as time goes by. One slightly comforting fact is that viruses that kill or totally incapacitate the host tend not to spread as much, for obvious reasons. So there can be a tendency for them to weaken with time, by evolution.
4) We don't know yet. But many viruses which are spread in aerosol form or by contact with door handles etc, get fairly quickly destroyed by sunlight, which is more intense in the summer. This is why seasonal colds and 'flu' are prevalent in winter.
5) It seems from what I have read that the very elderly and those with pre-existing conditions are most vulnerable. Aside from that, people are individual and the effectiveness of immune response varies quite a lot.
6) No. Such measures seems fairly useless. But washing your hands whenever you get back from public places (in contact with public transport, handrails, shop counters, etc, before they go anywhere near your nose and mouth, is a sensible precaution that will not make everyone think you have gone crazy.
If your wife is asthmatic, she might consider getting some medical advice.
But it is early days. We don't really know much about it yet. I think I'm going to avoid airports for the next few months and stop eating in the Chinatown area of London for a bit. If we get an outbreak in London, I am going to stop using the underground. But that's about it. From what I read, these masks don't do anything useful - unless you go for the full bio-hazard suit, in which case you must promise to send us a picture of yourself, for laughs.