What effect does curse have on double type Pokemon that are half ghost ?

Question

I mean it gets the bonus atk and def or use 50% hp to deal damage

Answer 1

the Ghost type takes priority over other types, so dual-type Ghost-type Pokémon use the Ghost version of the move.

So no, it will only get the "use 50% HP to deal damage" part, the dual type doesnt matter.

Source