The One Piece manga is not in color. It's presented in black and white, which allows for greater focus on the linework and details of the illustrations. Colorized versions might exist in some limited cases, but the majority of the manga is black and white.
The One Piece manga is mainly presented in black and white. However, sometimes there might be special color editions or promotional images released, but the regular series is not in color.
The law is definitely not dead in One Piece. It exists in various forms and degrees, and its enforcement or violation drives many of the story arcs. The struggle against injustice and the search for true justice are ongoing themes related to the law within the manga.
Not at all. Law remains a significant character and has many ongoing plotlines associated with him. His presence continues to shape the events in the One Piece manga.
Some fanfiction also pairs Law with Kid. Given that they are both Supernovas and have a somewhat competitive relationship in the main story, in fanfiction, they could end up as reluctant allies or even friends. Their combined strength and different personalities can create interesting storylines.
Well, in some One Piece Law fanfiction, there are concepts about Law's devil fruit powers. Writers might come up with new and creative ways he can use the Ope - Ope no Mi. For example, not just for medical purposes or combat, but perhaps for some unique forms of transportation or even creating alternate dimensions within his Room ability.