When you go on chemo your body goes into sort of a "cycle". You feel ok for the first few days, then your white and red blood counts drop on about the 10th day. (It's probably different for everyone) This is the time to avoid anything germy: crowded places like malls, movie theaters and restaurants and small children. Your body can't fight the infectious germs.
As far as I know, when they refer to avoiding the chicken, fish and beef, I believe they are referring to the "handling" of raw foods. My family would never let me touch raw meats when I was/am on chemo.
Then you go back into an "up swing" and you usually know you are doing better because you are "feeling" better.
It's better to be safe than sorry. I've taken all the precautions and still wound up in the ER with high fevers, neutrapenic fever and so on. And that is no fun.
The condom things is probably like the others said, you don't want to get preggers while he is on chemo and to prevent any infection to him that may be lurking, and in a "healthy" person would not even be an issue.
Hope this helps,
TAnn