Yes, if you like detective novels. The Cormoran Strike series has a good reputation for its mystery and character development, so this one is likely to be worth it.
The 'The Running Grave' is probably filled with the elements that make the Cormoran Strike novels so popular. There would be detailed descriptions of London settings, and Strike's unique detective skills would be on display as he solves a new mystery. The story might also explore the relationships between Strike and his colleagues or clients, adding depth to the overall narrative.
Yes, there will be. J.K. Rowling has been quite engaged with this series and given its popularity, it's very likely she'll continue writing more Cormoran Strike novels.
As of now, there is no definite information regarding a new Cormoran Strike novel. The previous novels in the series have been well - received, which might suggest that there could be more in the future. But we have to consider that the author, J.K. Rowling, is involved in multiple projects. She might be exploring new ideas or working on other stories. The publishing world also plays a role. If the publishers see a high demand for a new Cormoran Strike novel and if J.K. Rowling has the time and inspiration, then it's very likely that we will see a new one. But until then, we can only wait and hope.
I don't think so. J.K. Rowling seems to be taking her time between novels in this series. And since there are no hints or news about a new one, we may have to wait a while.