Giyu survives in the manga. The plot doesn't lead to his death. His character has many adventures and developments that keep him alive and active in the story.
Their relationship can be developed through shared experiences. For example, if they both get injured in a battle and have to rely on each other for survival while waiting for help. This would force them to open up and communicate more, breaking down Giyu's usual stoic exterior and allowing Shinobu to see a more vulnerable side of him.
A plot could revolve around a mystery illness that is affecting the Demon Slayer Corps. Shinobu, being the expert on poisons and medicine, tries to find a cure. Giyu gets involved when he discovers that some of his comrades are showing symptoms. Together, they suspect that a new type of demon or a hidden enemy within the corps is causing this. They have to investigate, and during this process, they face many challenges and also grow closer as they share their concerns and ideas.
One of the favorites is Batman comics. They have great art and complex characters. Also, the dark themes attract a lot of readers. The consistent world-building keeps fans engaged.
I have no clear idea. But usually, Manga Rock is a platform for various manga, and Last Embryo might just be one of the titles available or have no relation at all. It depends on the specific context.
To my knowledge, there haven't been any official announcements regarding the creation of new Samurai Jack cartoons. But you can keep an eye on related entertainment news for the latest updates.