A Probability Problem

Consider a party with n (perhaps n could be a 100) people. Every person has a different pair of shoes. Everyone takes off their shoes at the beginning of the party. At the end of the party, each person takes a random pair of shoes that may not necessarily be theirs.

1. What is the expected number of people that will have their correct pair of shoes? (Not necessary to include it in your topic or "Question" of your scientific method, but it should be a question that should be answered in your overall project.)
2. Suppose you hear someone in the crowd exclaim that they got their correct pair of shoes, but you do not necessarily know who made the exclamation. What is the expected number of people that will have their correct pair of shoes? What is the probability that exactly one person got their correct pair of shoes?
3. Suppose, instead, your best friend who is at the party comes up to you and tells you personally that they got their correct pair of shoes. What is the expected number of people that will have their correct pair of shoes (including your best friend as part of the count)? What is the probability that exactly one person got their correct pair of shoes (your best friend)?