You get +1 Action whichever option you choose. The options are +2 coins, or everything after that - discarding, drawing 4 cards, and other players discarding and drawing. A player who Moats this neither discards nor draws. Other players are only affected by this if they have 5 or more cards in hand. Other players can use Secret Chamber when you play Minion even if they do not have 5 or more cards in hand.
In an article on Board Game Geek, Donald X. Vaccarino commented on the development of Minion:
- The original version of this was a "choose one" card with three messy abilities. It was too messy and also too narrow, and so left. Later on I was looking for an attack to replace another attack that hadn't worked out, and thought of this. Originally the "discard, draw 4" ability only worked on yourself, but it seemed like it would make a cute attack if it hit everybody. The problem was that it was still too narrow - you would not always have a combo that made that exciting enough. The solution, proposed by Chris West, was to have the card be a combo with itself. You can play a couple copies for +$2, and then play one to get a fresh hand. For simplicity there is no 3rd ability.
- During development I had some games where it was clear that this card was too annoying. The "discard, draw 4" ability had no "5 or more cards" clause. So you would sometimes draw your whole deck... and also make everyone else draw their whole deck. So you'd make everyone else shuffle on each of your turns. As an attack it gets no worse if it just hits everyone else once, and it's way less annoying. We tested both and went with the less annoying version.