I would argue that Han Solo is a supporting character in Episode 4, because he does have an arc. He gets his money in the beginning of act 3, and he's going to pay off his debt, and that's all he wants. But Luke tries to convince him to join the Rebellion, to fight for something greater and help his friends. When Han comes back and rescues Luke in the climax, he's discovered his need: Luke was right, and fighting for his friends is more important than just the money. That's a character arc, which elevates Han to a supporting character.
Let's say I'm writing a heist script. I'm writing it because I love heist movies. I don't really have anything big or important to say besides heist movies are cool. How do I work out a theme?
I would guess 5 words total, since if they have multiple lines it's likely they'd get paid more either way. But don't take my word for that, I'm just guessing.
