Well, the return date of One Piece manga can be hard to predict. It often depends on the creator's schedule and various production factors. But usually, there are hints and teasers released before the actual comeback.
I'm not sure exactly when it's coming back. You might want to keep an eye on official announcements or manga-related news sites for the latest updates.
Law's back story is typically presented in episode 660 or so. But be aware that the specific episode can change based on factors like edits or regional variations.
Nico Robin was the sole survivor of the Ohara incident. Her mother was a scholar on the island of Ohara. The World Government feared the knowledge being explored there, especially about the Void Century. Robin was just a child when she witnessed the destruction of her home. She was then on the run, constantly hunted. She had to rely on various pirate crews at times just to survive, all while being labeled as a 'devil child' because of her ability to read the Poneglyphs, which are ancient stones with important secrets. This difficult past has made her a very complex and strong character in One Piece.
The destruction of Ohara is crucial. Robin was just a child when it happened. After that, she had to learn to survive on her own. She faced betrayal from people who were afraid to be associated with her. Her decision to keep studying the Poneglyphs despite the danger was also a significant event. And finally, her encounter with the Straw Hat crew and deciding to join them changed her life for the better.
The key element is Arlong. He dominated Nami's village and made Nami's life miserable. Another key is Nami's love for her village that made her endure so much.
Nami's back story is really sad. She was originally from a village that was constantly oppressed by pirates, especially Arlong. She was forced to work for Arlong to try and buy back her village's freedom. She had to steal from other pirates, all while hating what she was doing but seeing no other way to save her home and the people she loved.