There are many important moments in the story, but the most crucialâ€”called â€œstory spotlightsâ€â€”are shown on cards. These cards have the Planeswalker symbol in their text box; this symbol has no effect on gameplay. You can read more about these events in the official Magic fiction at http://www.mtgstory.com.
The number of cards in your hand is counted only as Fateful Showdown resolves. Fateful Showdown is on the stack at this time, so itâ€™s not counted.
If Fateful Showdownâ€™s target becomes an illegal target, you wonâ€™t discard your hand or draw any cards.