Yes, you can play Hearts of Stone after the main story. It is an expansion that offers additional content independent of the main story progression.
Yes. The expansion Hearts of Stone provides extra content which is separate from the main story. Once you've completed the main story, you can still dive into Hearts of Stone. It presents new challenges, interesting characters, and unique quests. For example, you'll encounter new foes and have to make different choices that will shape your experience in this expansion. So, it's a great addition to the game even if you've already finished the main story.
Sure. Hearts of Stone is designed in such a way that it can be accessed even after you've completed the main story. It has its own quests, characters, and storylines that you can enjoy regardless of your progress in the main part of the game. This allows players to further explore the game world and experience new adventures long after they've finished the base game's main plot.