If I’m instructed to discard a random card from my hand and I only have one, do I still do that? 2.With…

Yes, even if you have 1 card in hand when you have to discard “at random”, you still discard the card. 2. First a minion engages a player, then resolves its “When Revealed” abilities. Quickstrike triggers upon engagement, so Hellcat’s Quickstrike resolves first, then her “When Revealed” ability.