Well, perhaps it could involve Damon and Elena finally exploring their feelings for each other without the complication of Stephen's presence. They might start to build a deeper emotional connection and face new challenges together in the town, like dealing with other supernatural threats on their own.
Yes, you can usually stop in the story in 'Days Gone'. There are various save points and breaks in the gameplay that allow you to pause your progress through the story. For example, when you reach certain safe houses or complete specific missions, the game auto - saves. This gives you the flexibility to take a break and come back to the game later without losing your progress in the story.
Partly. The movie takes elements from various real cases and weaves them into a fictional narrative. So, it's not a direct retelling of one specific true story, but has roots in reality.