I used to live in Rio some years back. Crime has certainly increased since I was there, but it is not as bad as it is often painted. Pickpockets and begging children are certainly not exclusive Carioca problems. It can be devastating at first, but surprisingly you soon get hardened to it all and you will find the positive side. One thing you will encounter is the incredible hospitality and friendliness of Brazilians. If your husband works for the government you will probably be involved with the local ex-pat community, but don't just stick around with them, get out and meet Brazilians too. Learn a bit of Portuguese. Try to blend in with the locals.
I've lived in South America for 28 years total, and never had a shot. Often it's a matter of perception. If you feel nervous without shots, then get them. If you are going to the deepest Amazon jungle, then some shots may be recommendable.
Niteroi is considered by Cariocas as essentially a dormitory town across the bay. Jokingly Rio people say there is a sign at the Niteroi end of the bridge that states "The North-East Starts Here". You will understand that when you get there. Although Niteroi is a city in itself, many, many people cross by ferry or over the bridge to work in Rio. This makes Niteroi less susceptible to crime and violence, and hence safer. That's not to say there is no crime at all, of course.
Water is also a perceived problem. All major cities in the world have similar water purifying systems, so Rio's water is probably as good as any city. Nevertheless, if you feel nervous about drinking the water, then by all means stick to bottled water. It's cheap enough in Brazil. I live in Miami. I drink tap water, but am in a minority. Some people look at me as if I'm crazy to trust the public water system.
The last thing you should worry about in Brazil is the food, which is probably much healthier and fresher that the food you eat in the United States.
See the travel blogs starlagurl sent for suggestions in Rio.
I found this great blog from a Canadian couple who moved to Rio a year and a half ago. http://dailyriolife.typepad.com/my_weblog/