Starting process. What to expect?

We have one child and are looking at starting the process of foreign adoption and wonder what types of things to expect in the home study and background check. We've lived in our current state for over 8 years. Will they need to run checks from our prior states of residence (criminal/social service - may need to look up some old infor for past states of residence)? How much do home studies cost and what do they usually include? What else should we ask about?