Havdalah begins when three stars appear, marking the end of Shabbat. It involves a glass of wine, box of spices, and singing of blessings. For more information, please see this resource: https://www.myjewishlearning.com/article/havdalah-taking-leave-of-shabbat/
YES. Havdalah and the wedding ceremony will have food. We want you well fed and happy :)
You can email us any questions directly (Sarah may respond) stewartandaliza@gmail.com