We were childless for our adoption, so I can't help you re: what they will ask the kids. As far as how to handle the home study, just relax and be yourself. They WANT to approve you. I thought they were looking for things to find wrong w/us, but that wasn't true at all. And we learned so much during the process, including thinking through parenting issues like how to discipline the child. So, I guess you'll have the advantage of knowing some of the answers.
Good luck w/your adoption!!
- Faith