If you get a new job and travel to new countries after you apply but before the interview , do you have to take all this info for the interview also ? Any experience with this ?
You answer truthfully and if they ask, you tell them what countries you have gone to. Why hide it. US immigration officials will find out. You are interviewed by US and Canadian officers.
I have been to two Nexus interviews, and so have my kids. My child was 5 at his first interview. And yes, they asked the kids questions. Some were funny. What do you want to know? Answer their questions. They will ask about you about your travel, job etc. It is not stressful.