I heard back around one month after I submitted my application and there was one single interview before I was offered the position. I was interviewed by someone who was a peace corps volunteer maybe 10 years ago, they served in a different region of the world than I applied to, so I didn't connect to them much. They offered me the position a few days later and gave me only a few days to decide whether to take the position or not.

Peace Corps sent extensive interview questions ahead of time in an email. There were many question but the questions were the exact same as the questions in the email. It was very helpful!