If you have fewer than four cards in hand as the first ability resolves, you won't gain any life, but you won't lose any life either
You can even choose characters who don't have official names, as long as they're clearly defined characters, like the Wanderer
First Tyvar, Jubilant Brawler and now, potentially, Agathas Soul Cauldron
You can treat a learn card as a card that has some minor value effect like draw a card or create a token that can tutor for a lesson card from your sideboard
At their core, Mill decks are Burn decks, not combo decksboth are trying to count to a specific number as quickly as possible without much in the way of on-the-board interaction
Between burn and straight-up prowess decks, there are plenty of uses for a hasty 1-drop with the potential to be hitting for 3 or 4 damage