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Unless a trigger specifies otherwise, it will default to after succeeding. So you need to win the duel for it to happen (some triggers are after resolving so you don't need to win, and some are immediate so they happen immediately, again no success required). Then you always need the suit in the duel total to declare a trigger but Hoffman has a tome built-in, so unless something removes that he'll always be able to declare spool up.
Yes, you got it.
Again, yes. As long as you have a power token, you can do that.
There are various other ways to again additional suits. You've see it with Hoffman (built in), Vanessa (an ability). Henchman and Masters can spend a soul stone to add a suit while also getting the suit from the card. Power tokens can add suits. There's many other ways (it's one complex game). In the Ronin's specific case I don't believe it's possible to get more than 1, but other models that can use the same trigger.