Yes, Snapchat allows you to see if someone has replayed your snap story. There is an icon or indicator that shows the replay action. However, this feature might be subject to the privacy settings of the app and the individual's account settings.
Yes, you can find out. Usually, Snap will notify you or show a list of people who replayed your story. But keep in mind that the way it's displayed can change depending on updates to the app.
On some social media platforms like Instagram, currently there is no direct way to see if someone has replayed your story. The analytics usually only show the number of views, not replays specifically.