Up to you, she just needs to be freed for most of her attacks to do any good.
Also, could you specify which attack King is supposed to be using? He’s got multiple moves that could fit that description.
Yes you can, if they’re just being sent out and not replacing a Pokémon already on the field. So right now you have Leo and Princess out, if you send out Hero and Dancer in addition to them, then they get to attack, but if you recall Leo and Princess to put Hero and Dancer in their places then they don’t.
Let me know if that doesn’t make sense, there’s been confusion on that in the past.